Slip 'n slide seat back

Recently went camping in my new to me DCSB, just me and the doggo, so I folded down the rear seats to stow some things like food bins, a 12V Dometic fridge, small plastic tool box, Goal Zero Yeti power pack. Realized right away that the seat back was pretty slippery and things were going to slide around, so I put piece of remnant outdoor carpet down but that had kind of slick bottom to it so it didn't do much good. I've been brainstorming some ideas like putting down friction tape, velcro-ing pieces of carpet down, cutting a board to size and covering it with some leftover speaker box felt that I have. I'm curious if any has any solutions to offer that has worked well for them? Or maybe I should just keep the seats up? Thanks.

 

Sounds like some rubber mats would do the trick. Think bed mat, but for the back seats.

 

Shelf liner stuff works well for slipping i have small pieces cut under my couch feet so it stays put on the hardwood floors

 

Tool box liner