I believe the laws vary from state to state. The main issue is from a safety aspect. If you want to use a bench seat facing forward, there isnt adequate room for an emergency exit, if a bad situation should arise. Although ive seen a guy with a hz sandman that has mounted his bench seat sideways in the cargo area and may have passed registration, but i am not sure. Seat belts need to be securely mounted as well. Theres a few things to think about. Maybe speak to your local engineer for solid advice.

Hope that helps