Came here to ask for exercises, descriptions, illustrations, anecdotes, etc on how to ride the hind end. I’ve been riding all my life but this is something I haven’t been able to get a grip on and for my horse’s sake I need to study this more. I’ve always been one to ride with the reins too long. When I got my young horse back from being started under saddle I was shocked at how short they wanted me to have the reins. She even put tape on my reins so I would have a reference. I mention this only because people tell me I’m riding his front end.
I can feel his front end just fine. At the walk I’ve been able to isolate my hips and their movement to his hind end. But I still don’t know how to influence his hind end specifically. Maybe I’m over thinking it.
He’s developed into a really nice horse, he’s generally very soft in my hand and has a great way of going.
I do work with a great trainer but this is something I’m studying outside of our lessons. 
Spankie Starter Test
This is our dressage test from 12/4. He did very well and got a 30!
Do you know the timing of the aids based on where the hind leg is at all gaits? As an example you would want to half halt in the canter as the outside hind is under? And yes you need the shorter rein or the half halt may not go anywhere. There are articles and videos out there that will help explain. Having mirrors or a ground person is helpful!
Over thinking it. Just think to push your horse into the bridle rather than pulling. So if your horse is moving forward with rhythm, suppleness, impulsion, straightness (note the list is out of the usual order because it is a dynamic process) then the reins should be the means to have a two way conversation i.e. contact. Short reins do not mean you are on a contact, it means you have short reins. Putting tape on the place where someone else is riding at a good length is rather pointless because your best length will probably be different. Moreover, the horse will have an opinion about where he wants your hand to be. On the other hand, reins that are long and floppy don’t help a horse because it makes it harder for the horse to gather his energy and balance whilst carrying your weight and trying to do whatever you are asking.
The only timing of an aid I can remember is to use the inside leg when the outside shoulder is going forward for a leg yield at the trot. Everything else, no idea. 
LOL! Ok then, see if you can find a video explanation of the timing. I learned it from my trainer when I first started dressage training. It’s important because you can block the momentum if your timing is off. This is where dressage becomes so important!
I’m with Willesdon, you’re mostly over thinking it.
“Riding the hind end” is one of the many euphemism that we use to try to explain something difficult to identify. “Riding back to front” and “riding into the hand” are others that trying to explain the same phenomenon. And it is one of those thing that you never finish learning or developing–so it isn’t like one day you will get it right.
It’s really about energy and energy flow. Energy is created through the pushing off the ground of the hind feet.The energy should travel up the hind legs and over a lifted back and neck into a restraining/connected, but not pulling hand. If you are pulling the head or neck into a position (as oppose to pushing the hind end into the hand) that’s riding “front to back.”
I think Wofford demonstrates this with a whip, when you push on one end of a whip while holding the other still the whip bows up. In physics we could talk about the bow being a demonstration of stored energy. But if you let the front hand go the whip flattens and there is no stored energy.
That was a lovely lower level test and there was nothing wrong with it. To continue to move up and improve we would want to see the horse beginning to lift his back and “stretch over his topline.” (another euphemism.) If I were in your shoes I’d work to teach my horse to stretch. Bad angle, but the walk across the diagonal should have been the place to show that off in a low level test. Yes, those stretchy circles are very key in how a horse powers from behind and lifts his back. (You cannot pull your horse into stretching over the topline!).
I would recommend you read some dressage books and concentrate on basic theory. What you are asking about is really some of the very essence of what dressage is/or it trying to accomplish.
You turn the shoulders more to get more hind end feeling. Thats why there is a turn on the haunches in tests. Then you get on the haunches and feel it. Then you start those canter deoarts from that feeling… then you have a whole new collected canter button.
