Yes, more than english, less than western, secure, comfortable and light weight. Kinda the best of both worlds. These are made in the US and you can pick the tree that fits your horse best by use of Fit To Be Seen Forms.
You may find what you’re looking for in the Sensation English Dressage saddle. It’s treeless, but has a fairly narrow twist, straight leg, English style billets, and overall a very “English dressage saddle” look. It also comes with knee blocks that have a velco backing so they are easily removed and replaced as desired. They have three dressage styles to chose from - any one would probably suit you. You can get them on trial to see if they fit you and your horse’s type of riding.
I do trail ride in one (Dressage Trail), and adore it. An endurance friend let me try her’s and that was all it took. My horse said YES to it, and so did I. 
Sadly my County Competitor was hurting my guy’s back, and no matter how hard I tried to mitigate the issue, the problems just wouldn’t go away. Plus I was finding that the County also was hurting my back when I spent long hours on the trail. I did try the Arabian Solstice and liked it, but my horse didn’t.
The Sensation is super comfortable for both my (non-gaited) guy and myself, no matter how long the hours on trail. I know a gaited rider (Paso) who uses the formal model and adores it. Her horse loves it too - he moves very freely and easily with it. The two never found a treed saddle that they both could agree upon.
Here is their “formal” dressage model, and the less formal dressage model. Here is their a Dressage Trail model which is what I have. I also have the forward seat model for foxhunting. LOVE it! I can go for hours and hours painfree. So can my hunt horse. We’re always the last to go in when the huntsman calls it a day, and we’re still as happy and chipper as at the beginning. And we never have to stand in the saddle to relieve a sore butt…because no part of our anatomy is ever sore now! 
I’ve got an AERC friend who does 50’s, a few 75’s & now a 100 in her dressage saddle. It is leather & she uses a cool back saddle pad.
She is comfortable, secure & I’ve never seen her balance anywhere other than centered. Right where it should be.
Experienced endurance riders will tell you to use what you have to start the sport & if it ain’t broke, don’t fix it.
If you’re really ready to make your own saddle, contact Smith Worthington. They make beautiful saddles and can work with you so you get exactly what you want. I have a SW AP and their dressage saddle and love them both.
On their clearance page they have a couple of their saddles made especially for mounted police:
http://www.smithworthington.com/index.php?p=product&id=536
Deep seat and your choice of English or Western rigging. Don’t necessarily be put off by the 18 1/2 seat size; I’ve found that in their deep seated saddles I needed a larger size.
Their Stellar Solaris is also a good trail choice:
http://www.smithworthington.com/index.php?p=product&id=719
The only drawback I can see to trail riding in a dressage saddle is the lack of places to to attach things like water bottles, etc. but there are ways around that. http://www.sstack.com/Western_Trail-Riding-Accessories_Bags-for-Trail-Riding/Dura-Tech-Trail-Boss-English-Cantle-Bag/?utm_source=bizrate_com&utm_medium=shopping&utm_campaign=WEB01010PS8&scpid=6&scid=scsho7992545 I say if a saddle is comfortable for you and the horse, ride in whatever you like.
For curiosity’s sake you could look at the Pandora endurance saddles. They are pretty cool -
[URL=“https://www.google.co.nz/url?sa=t&rct=j&q=&esrc=s&source=web&cd=3&ved=0CCkQFjAC&url=https%3A%2F%2Fwww.facebook.com%2FPandoraPerformaceSaddles&ei=2H9AVYKwOsW_mAWIooDwBA&usg=AFQjCNHwP97Zsfup_PWUYcUmLwmvFc-ZpA&sig2=75krV3CJnYRfATFG7X7u0A&bvm=bv.91665533,d.dGY”]
Pandora Performance Saddles | Facebook - lots of chat and pictures.
I ditched my deep-seated dressage saddle recently, and trail riding was one of the reasons. It was a very comfortable saddle; I could ride in it for hours. BUT a couple of experiences with my horse flipping out, and realizing there was NO way I could get out of that saddle unless I could get her calmed down was the beginning of the end for that saddle. (For that matter, it was hard for me to get out of the saddle even when she was standing still and calm. My hips complained a lot about dismounting.)
I am – tentatively, I don’t want to get into it here – now riding in a Black Country Celeste A/P with some semi-custom modifications to make it fit me better. It’s perfect for my position and very comfortable even with the medium-wide twist.
Thanks Quietann a few people have made similar comments. I’m afraid i don’t feel secure in a AP saddle due to weak legs but western hurts my knees/hips. Really stuck now that my old reliable Steele plantation saddle (english rigging)doesn’t fit my new horse. I was looking a the newer deep seat dressage saddle but I agree with your comments andthink i’d feel too locked in one position for a long ride.
I had an AP custom made for me and my horse as I couldn’t find exactly what I wanted to trail ride in off the peg. I ride in very rugged country and couldn’t bring myself to subject my dressage saddle to those conditions!
I got a deep, soft seat, nice knee and thigh blocks. It is a secure sofa :). I used Matt at Heritage custom Saddlery in England. Google it, he has a good website, and was very helpful. He has a trail saddle model that might work for you with some tweaks, too. The price was very reasonable and it took about a month to come in, and it fitted us both perfectly right out of the box.
I use the 90 degree offset stirrups, which save my knees and ankles from much pain.
Or, have you tried an Aussie?
[QUOTE=Bombproof;8117470]
The only drawback I can see to trail riding in a dressage saddle is the lack of places to to attach things like water bottles, etc. but there are ways around that. http://www.sstack.com/Western_Trail-Riding-Accessories_Bags-for-Trail-Riding/Dura-Tech-Trail-Boss-English-Cantle-Bag/?utm_source=bizrate_com&utm_medium=shopping&utm_campaign=WEB01010PS8&scpid=6&scid=scsho7992545 I say if a saddle is comfortable for you and the horse, ride in whatever you like.[/QUOTE]
I have one of the packs like you linked.
I ride in a AP saddle but I just had Beval Saddlery add 2 D rings on each side. I figure old time foxhunters had a sandwich case and/or flask that attached to the D’s.
I had a facebook friend recently make comments about saddles with huge blocks being for people who can’t ride. :no: My large blocked Wintec Isabelle saved my butt more than once when my mare decided to try to scoot out from under me. I also put a lot of trail miles on it and found it super comfortable, and that deep seat and big blocks were nice to have during steep decents. Sydney once laid down with me during a water crossing (bad pony!), and I was so thankful for having a synthetic saddle. I was able to hose the mud off of it, lay it out to dry, and it was good to go again the next day with no ill effects.
If a true dressage saddle isn’t comfortable on long rides due to the openness of the hip… or… if it’s not suitable for the terrain you’re riding… you might try an AP or eventing saddle that is leaning towards dressagey. Something shapes like the Collegiate Senior Event, or some of the older Stubbens… it would allow you to get off the horses back when needed and be a bit more comfy through the hip on long rides, but still have a deep secure seat.
[QUOTE=walkers;8131044]
I was looking a the newer deep seat dressage saddle but I agree with your comments andthink i’d feel too locked in one position for a long ride.[/QUOTE]
IMO a dressage saddle may work, but it depends on a lot of variables. If you already ride with a very long relaxed leg, and are comfortable there, then the deep seated dressage saddles with the big blocks might actually be fine for you. The problem with that style arises when riders who aren’t very flexible through the hips rely on them to force their leg into position, esp on gigantic warmbloods that need extra wide trees.*
If you have a narrower horse, a narrower twist dressage saddle that fits him, and reasonably flexible joints you’ll probably be fine. Some of them (am thinking of Bates here, but there are probably other brands as well) also have adjustable/removable blocks, so if you find that you like the deep seat but the blocks are too restrictive you can move/switch to smaller/remove them entirely.
*For example yesterday (I work for a dressage trainer and exercise the lower level horses) I did two trail rides out in the desert, one on a 16h WB who is neither wide nor narrow and the second on a 17.1 WB who could fit a wine barrel inside his ribcage. Even though the saddle was more restrictive on the first horse I was still perfectly comfy after 2 hours, however even with a ‘flatter’ saddle on the second horse I was aching after 45 minutes.
