Would that cause the back of the saddle to put more pressure on the loin area since that part of the back is already elevated?

My boyfriend's rope horse is a bit downhill, and when he was using him every day on the feedlot he started having back soreness and galling issues over the withers, loin, and in the cinch area (it seemed like the saddle was always tilting and sliding forward).

A lot of times these horses are also much wider over the loin than they are closer to the withers. I mean, horse's backs are normally pear-shaped, but it's often exagerated in downhill horses. So the first key is making sure the saddle is wide enough over the loin, and it's not rubbing there because it's too narrow.

Two things made a big difference for my boyfriend's horse. I got him a wither riser pad (just an inexpensive foam one from Horse.com, made by Roma). And I made a centerfire rigging converter for his saddle, which pulled his front cinch farther back. You can buy the converters as well, but I made his using the round rings from a cheap cinch, latigo leather, and a couple breast collar replacement straps. Huge difference! No more soreness and galling.

A lot of the loin rubbing and soreness is from the back of the saddle popping up and down, and it will also sometimes "wag" side to side as the horse swings each hind leg forward. The riser pad helps the saddle sit level so the back doesn't pop up. And the centerfire rigging helps evenly distribute pressure through the whole tree. Also, make sure the back cinch is snugged up.

As a note, his Martin roping saddle with the adjustable gullet fits this horse really well and doesn't have any soring or rubbing issues. It's great for roping, but unfortunately the leg fenders aren't very free swinging, so my boyfriend doesn't like using it for his everyday riding saddle. He uses the centerfire converter on his other saddle.