[other tom]

A friend of mine did sort of what you are describing to two separate 20's. He had a bracket designed and built which extended the hull's running surface and was full-width. It even had the chines from the hull molded in and drain plugs (2, 1 for the bracket, 1 for the hull plumbed to the "real" transom.). Bracket aft end was about 4" above waterline, he then mounted small tabs on the aft side of the "extended" transom. The boats were beautiful, he had a 225 on one and has a 150 on the other. Both boats are in Stuart (I passed one going to Islamorada today) His name is John Vance, president of Jim Smith Boats. (772-286-1172 if you want to ask some questions. Total length was just under 23'. they floated very well, no wet feet. The loads on the new running surface are substantial, so I don't think you can do what you are describing by "glueing" on some buoyancy to the sides of a single-wide bracket. I rode in the first one, it performed flawlessly...