I am looking into building a tent rack for my truck bed that will line up with the cab height. I have an 8 foot bed on my truck and would like to go ahead and run it the entire length. But I want it to be light enough I can take it on and off as needed. I have been looking at using Aluminum as it is light weight and inexpensive compared to steel, and T-Slot in particular as I would not have to weld, which I do not know how to do.

I was looking at 0.75" x 3" for the base along the bed rails, two sides and the front, but what about the top and the legs? Would 3" x 3" in the corners and 1" x 3" in between be overkill? Could I get away with 2" x 2" or smaller in the corners and between the corners? I was figuring 24" centers for the sides and putting two supports in the cab end? Any of you structural engineer types be able to help walk a guy through this process? As for top rails and crossbeams, I know the layout, but again have no idea what size material I need because I do not knopw how to calculate the load or account for both Dynamic and Static loads.

I know I can probably buy one for cheaper than I can make it, but I need to work off some extra energy in the evenings and want to build versus buy.