Cargo liner ideas

Looking for some ideas here. I have the back seat removed and a piece of plywood in there creating one large flat surface. I'm looking for a rubber type material that can be trimmed to fit this entire area. I've been thinking about a gym may, but some of the reviews speak of a rubber smell to them.
Any other ideas?

 

This is offered with an adhesive back you could permanently attach to the plywood.

https://www.hydroturf.com/category/hydro-turf-sheets/sheets-boating/

 

Truck bed mat 3/8” thick cut to fit, with a piece left over for a pull out cover for my dog. Works great for my needs if i need the back seats up, i just roll it backwards. I ordered it off of Amazon, measure for your needs then search for that length.