Difference in Draft bars and Horse bars

Okay, I am trying to start riding my Perch John again with a roping saddle we have on hand. I am looking to get a draft saddle made that will fit him properly but I am wondering something. I know that draft saddles are designed especially to fit their shape but..... Do they sit where they should and still provide enough room for the shoulder to move freely (if fitted properly)?. Do they feel like they are kinda slipping back and forth to the sides or are they sturdy and solid? The saddle I have has a super wide gullet but is still just a FQHB saddle and I have to sit it farther back on him for his shoulders to have the movement they need. Can anyone post a good pic of a draft tree (without the rest of the saddle) so I can compare it to the shape of a regular horse tree?

Silly questions I know but I am just wondering if I shell out the money for a new saddle if I am still going to have to deal with the saddle slipping around on his back.

Thanks

They're usually wide, flatter angle, and with more "rock" to the tree and flare to the front. I'd find a dealer that has draft saddles that you can try out to see what fits. Abetta makes a nice synthetic draft saddle.

If the saddle fits and is balanced, it will be nice and stable.

If the draft trees don't work, I'd suggest going treeless .

For my Clydesdale and my friends Percheron I use the same saddle. It's an extra wide tree and I can measure it when I get to the barn later if you'd like.
Sissy my friends Percheron has an extremely wide back and this saddle doesn't slip or slide around at all and it doesn't pinch her either. It's an all purpose English saddle though. It fits just the same on Caleigh my Clyde and she doesn't have as wide a back but still she's built like a Clyde.
Before I got that saddle which I absolutely love I tried a couple draft saddles and they slid around under me. The ones that fit pretty well were the draft Aussie saddles. The ones with horns didn't but the no horned Aussies fit but they were way beyond my budget.
Drafttack.com has some good deals at times and I think you can custom order too? I found the Aussie saddles on there but I got my English saddle from someone on equinehits.com