That should make a super dock, I was planning on doing the same thing and found a really nice one in Iowa on the facebook marketplace, like a 24 fter, I won't be able to get up there and pick it up but for an 8x24 aluminum dock, they were asking 1000.00 for it, you cant build any frame with floats for anywhere close to that. this one already had some kind of floor on it but I don't know how good it was.

All the really good ideas I've ever had came to me while I was milking a cow.