Originally Posted by aquaman

I'm going to need to make an empty 350 mile trip down to LA shortly.

I'm tempted to take a sheet of plywood and strap it down on some 2x4 legs to be level to the top of the box. Would it yield any practical mpg gains?

The box is wider than the 4x8 sheet, so there'd be 2 long open gaps down the length of the box. It is specifically a quick and dirty temporary 30min setup made of scrap wood that I have lying around. It'll remove since I'm hauling stuff in the back most of the time.

Any of you guys try this and see any benefit/difference?

thanks