Thanks for input but I think I will try with ABS and see how it works. I plan to use 1 1/2" for 4 vertical legs and short sides, and 2" for the 8' width. At the very least I can use it as a mock-up and experiment before spending big $'s on a proper bimini.
Sumner, yours looks nice and adjustable fore and aft. I am going to make something higher so I can stand in cockpit under it - 5' legs.