I have a custom 30" setback 5083 and 5086 aluminum alloy bracket for sale. I don't want to cut it down to 24" setback for a 20 footer. The flotation tank is big, it is aluminum MIG welded inside and out, and it is made of the same aluminum they use for buoys. It has sat outside for 3 years and still shines. I bought it, cleaned it up a bit, but no longer have access to the sort of tools to tweak it for a 20 footer. It would be great for a 23 footer. I have some 6" radius 5083 stock as well, if someone who can weld aluminum wants to make nice corners on the swim platform. It is also lighter than most fiberglass brackets.
I am asking $900. It is north of Boston, but I can deliver locally, or meet someone.