I am 6' tall, my build table is 3' high and I mostly build with internal strongbacks. This is a good all around build height for me. When scraping the insides I clamp two "U" shaped stands on the table with a strip of carpet stretched between the tops of the "U". I can slide these brackets closer or farther apart so the uprights do a good job of damping the "swing" of the kayak when I am working on it. I also clamp "stop" brkts on each end of the kayak. By lengthening or shortening the carpet strips I can raise or lower the kayak as much as 8" and I can also turn the kayak up on its side to make working on the inside easier yet.
I am 71 yrs. old and bending is not as easy as it once was, same for getting up from my knees but . . . . . the saying goes, "use it or lose it." With that in mind I guess I will keep flexing my body as needed, even though I do groan sometimes :)
Randy