My name is Michael and I just installed a Intex Ultra frame 18'x54" AGP. I used all your methods and it worked great. My problem was after the water was added and all was settled.
Being that I used at least a 4" base of compacted sand in a 20' circle, I used small 6"x8" pieces of plywood under each of the 18 legs and kept it away from the liner as you suggested and then leveled each leg. Well after filling the pool, the legs seemed to out and the plywood moved in so now the plywood is under close to half way under the liner and I feel them when I put my feet on it, some are hard cut and seem to feel the points and edges, not real pointy. I did place the plywood under the tarp that came with pool. Should I jack up each leg as you have in your diagram and pull the pieces back away from liner now that the pool has settled, can I do that without draining all the water. Or do you think it will be ok without doing anything. I'm just afraid of after time the edges piercing the liner.
the picture I added is how it looked before the leg slid out after filled and the plywood slid under the liner, also I didn't have the legs screwed to the plywood as this person did in the photo.
Please advise if you can,
Michael in San Antonio