I've always just rolled out my 4' wide by (whatever you cut it to long) rubber mats for overnighters or long trips and keeps the inside from getting slippery.
I have a big hexagon tent too and I run 2 rolls down either side and put the holes in a line down the middle leaving a gap there - but you could cut it once you figure out "the perfect layout" for how you fish.
I've tried the foam interlocking squares, plywood and other stuff and I keep coming back to the roll up mats ..... they come in different thicknesses and grip patterns and are sold in various widths and by the foot.
https://www.princessauto.com/en/deta...t-/A-p8681645e
After you are done with them roll them back up and throw them back in the truck bed without the fear of them flying away on you down the highway ..... lol ( not that that's ever happened to me or anything).