Material choices for homemade rack platform base?

[DaveM]

I have a pair of 1.5" x 1.5" (1/8" thick) aluminum square tubes that I want to use to make a narrow rack platform for my truck. Trying to get something done in the next few weeks before a road trip in mid July. The platform will be about 20" wide and 60" long. It will carry my two small water tanks, extra 3gal fuel can and small action packer or rubber maid tub with camp supplies. Not a big load and not really being used for anything more than road trips and general camping.

My idea is to use the two aluminum tubes as the sides and attach a base made of either plywood or aluminum tread plate. I'm not satisfied with the quality of ply I can get locally (poor quality exterior ply, or high quality cabinet ply but with no exterior glue) and tread plate is more money than I would have thought for such a small application. Curious if there are any other options I'm not thinking of. My goal is to be able to attach the base myself with bolts, no welding. And trying to keep material cost under $75.

Any ideas on other materials or methods of creating the base? I've though about aluminum cross trips but I think that would only really work well if I could have it welded which is definitely out of budget.

[John E]

Are there any plywood specialty stores near you? Some 13mm Baltic birch would work and shouldn't cost too much. Get a quart of exterior oil/poly finish and make sure you cover all the seams, edges, and any holes you cut or drill in it with a couple coats and use stainless steel fasteners.

[DaveM]

That's a possibility, there's a McBeaths Hardwood in SF. No Baltic but they sell Finnish Birch (exterior) as well as few marine grade plys. The marine grade stuff is too much money but the Birch may be ok. Only comes in 12mm and 18mm. I think 12mm would be ok.

[KAILUAZ]

What did you end up going with? I'm looking at making a storage system and figuring out what materials to use.

[DaveM]

For a short term solution I just ended up using 3/4" exterior ply, painted with grey rustoleum. I may eventually source a piece of aluminum tread plate but for now this is working great.

[jronwood]

I know it may be too late as your date posted, but I too am trying to decide on materials, I have made few steel boxtube/expanded wire welded units, and they last, but always need annual (ish) touchup, paint/prime or even complete sandblasting. I am thinking perhaps aluminum, but need to teach myself to weld it with my spool gun which I have never used...... So what DID you do?

Jronwood