If this is a western saddle, do you have a rear cinch? And is it tightened up enough to actually DO something ?
Britchin...breeching. Seem to be the same thing. I had to look it up.
The saddle is a Tucker Plantation with one girth/cinch. But it does have lots of handy rings to tie to including one center behind the cantle. So, if there is no back cinch to hook to, then maybe the crupper will be the way to go???? Dunno, but I will be researching as I am tired of buying what is not the best choice and then having to purchase something else that I should have gotten in the first place. (I don't suppose anyone else ever has that problem.)
Yes, britchin and breeching are the same things. I think britchin is a regional thing.
The back cinch is for the purpose of keeping the back of the saddle down on the horse's back during high torque situations like hard rollbacks (think of cutting a cow) and roping. The purpose there is to keep the bars of the saddle flat on the horse's back so that there are no pressure points under extreme stress. They do provide a little bit of added stabilization during normal riding, but to prevent a saddle sliding forward on steep declines; well, that's not what they are designed to do.
I never tried to rig a contraption for a crupper because that would have required me to buy a crupper LOL. I always have tons of extra leather straps laying around so it was easier for me to rig up a britchin. I never just hooked it to the back cinch or the back D-rings. I had straps where I ran it up under the back cinch and it attached to the front rigging. Those are the ones that actually sustained the pressure. The ones that run up over her hips and attach to the back rigging are just straps to keep it up on her butt instead of letting it fall down above her hock.
How steep are these hills? My friend had a Tucker endurance saddle and that thing just wallowed all over her horse's back. Going downhill made it want to wallow foreward. I am sure it was part just a fit issue, but that was my second experience with a Tucker where it did not sit well on the back.
It depends on the horse and the saddle which is best. If the slipping is severe, then britching is better. If it just slips a little forward a crupper works well. A crupper ring is easy to have a cobbler or saddle repair person install.