Oh I ADORE him! OK, I love all things Morgan, but those Olde Tyme heavier Morgans are the coolest ever (in my book). Does he have Lippit lines? Doesn't matter what his lines are, he's Da Bomb! Sure-footed like no tomorrow, I bet?
That back isn't really that curvy. Get a saddle that can sit low enough in the front, and
I think it will be quite workable.
I ride a Morgan with the same build. Attached image. If he were mine, I'd go through the work of getting the right saddle. Because he isn't, I just slap a treeless English saddle on him. But I do know the challenge of that back.
If you consider Duett, contact Nancy at Duett. If she can't make it fit, no one can.
Frlsgirl, if you've gone through 20 saddles on your Morgan, you know far more about fitting these special horses than most. I hereby knight you... Expert Morgan-fitter.