Are you moving it inside your truck Mark ? If so, set it on the floor, with the rear panel facing the front seat back. If you hit the brakes hard the rear panel is what might touch the seat back. Put a piece of dense foam between the rear panel and the seat back. Otherwise it will just sit there and nothing need touch it. Blankets and such attract sand, dirt, etc. and make it difficult to handle a heavy item.
If you do get any scratches, Meguiar's Ultimate Polish will take care of them easily.
https://www.meguiars.com/automotive/products/meguiars-ultimate-polish-g19216-16-oz-liquid
Congrats on the score - that is an awesome sub !!!