Kid, he needs 3-1/2 x 1"....there are two 3-1/2 " legs with the 1" between.
the 1/8 " material would probably work, but the ID would be down by 1/16".
I am restoring a 90' Lowe 240 pontoon. There is a piece of the deck edging missing from one side. (4') this alum. channel is 3 1/2" X 1"X 3/32" I have looked everywhere and can not find any company that has this size. Anyone have any ideas????