bed and fuel filler advice needed
 

First off I know there are lots of threads on gas tank relocation, I have a question that I have not been able to find the answer to.

I have installed an older blazer tank in the rear and I think I have a good idea for a temporary (a few years as non-daily driver use) filler neck location. I just want to get some feed back before I go all in.

I will be installing a full sheet of plywood as a cheap bed without the bed strips. I was going to build a wooden box on the side for the fuel filler. I was thinking it should be 3-4 inches off the bed floor. I was thinking of using a marine Perko vented filler.

Is there any issue with using a plastic one? Issue with using wood as the support piece? would I just put the ground to another metal part?

Also, what type of plywood would be good? (I have not really searched this).

Thanks