So here is an update.
He got 5 days of nothing but being a horse. Then we saddled him up with a new pad and did ground work for about 15 or 20 minutes inside. Then he was led around the arena. Before leaving the arena, the saddle was loosened then went back to the barn. We did that for 2 days. For 2 or 3 of the next 6 days, trail riding ending with stopping at the arena gate and loosening the girth after standing still for 5 seconds or so, then led him back to the barn.
Today we had the chance to take the horses for a little trip. Trailered for an hour to a fairground. Got him out of the trailer and led him (no saddle) to the arena and just walked around for 5 minutes. then I saddled him up loosely and did the same. I finally cinched him up and got on. It helped that his barn buddy was with him. We walked around the arena and make-up pen for about 10 minutes then went and rode around the fairgrounds. We finished up by walking back to the arena gate to loosen every thing up before loading for home.
He bowed up a little when he was first saddled up today, but calmed down rather quickly.