Hi, I worked as a trail guide on the east coast some years ago so this is from that point of view. You may know a lot of it, but I gave you extra info just in case.
I think you should wear whatever you are comfortable in.
As far as staring or snickering, a lot of western horse rental places will roll their eyes when they see helmets or breeches. I wouldn’t worry about it. You are the one paying and it is your head.
You shouldn’t get rubbed in jeans- most western saddles will put you in a bit of a chair seat and the seams won’t bother you. You also don’t constantly rub your calves in the girth area when riding western b/c your stirrups are longer and on a trail ride you don’t need tight calf contact.
If you go through trails with brambles, they will grab your breeches and may put snags in them. If I were going I’d wear jeans, paddock boots, helmet. If I was going on a long ride, I’d wear a sweatshirt around my waist that can easily be put under my butt in case my butt gets to hurting. Day two of riding 3 and 4 hours a day, and you’ll really treasure the sweatshirt.
Other hints- make sure that you don’t make too big a deal of your ridinge experience, because everyone who goes there will tell them that they are advanced since they rode 4 or 5 times in their lives. This is sure to cause eye rolling and you will either get put on the same dead quiet horse they planned on giving you in the first place, or you will get stuck with an annoying head tossing horse that they reserve for the “professionals”- snicker, snicker. None of the horses should be wild, but some are more annoying than others.
Make sure you stay in line if they tell you to- a lot of hack horses will kick anyone trying to pass. If you have to pass, give the horse at least 10’ or more. Some of them will go out of their way to reach you.
For riding a horse with a western bit, leave slack in the reins. There should be a visible loop in the reins. You still have contact but it shouldn’t be a direct line which would cause the curb strap to constantly dig into the horse. Same as English, if you ask the horse to slow down and it slows down, reward it with releasing pressure.
Check your girth before you get on- some places aren’t so great about that. They will roll their eyes at this, but don’t worry- you are the one who will end up on the ground if the girth is too loose. If you want it tighter, you should ask them to do it in case your horse has any weird issues- and you prob don’t know how to do the western girth anyway.
Make sure your stirrups feel good and even before you head out. For my stirrup length, I stick my arm out with my fingers straight out and put my fingers up at the stirrup bars. Then I make the stirrup hit my arm pit. This is the starting point. From there you may want them up or down a bit once you get on. Make sure when you stand in the stirrups you are clearing the saddle, but you don’t want them as short as H/J flatting stirrups.
If you think your horse will run your knee into a tree and steering isn’t getting the job done, just lean over and push on the tree. The horse will be forced to move a step away and your knee will be safe.
If in doubt about something, grab the horn (as long as your girth is tight). Don’t worry, no one will know!
Feel free to post or not. Some of the horses may have nice QH jogs and you won’t even need to post.
You mount from the ground, so make sure your toes are digging into the girth or nothing, not the horse’s side.
Sounds like a great trip! Have fun!
You can find them locally at western wear stores, or order the online (I get mine from Valley Vet Supply, since they’re much cheaper there, ha.)