I believe Camp Trails was the first with the padded belt - or possibly Trailwise. Kelty was definitely not the first, I recall the old 2-inch webbing belts on the Keltys of the early 70's, which attached at the bottom of the frame rather than being a full wraparound belt. Then Kelty started padding those straps, and finally went to a full belt (albeit attached to the lower backband of the frame) somewhere in the mid-70's.
I first had a Camp Trails pack (1971) then a trailwise frame which I made my own bag for in 1973 or 74.
Reading Fletcher back then, I loved his writing and some of his tricks, but though his pack was awful heavy. Still like the writing. I actually wrote to him once, to say how much I enjoyed his book "River" about descending the entire colorado River, and recieved a very gracious reply.