It all depends on how you want it and how many belted seats you need .. I’ve got a traffic and have 3 seats in the front, a table and 3 seats in the back with a bed made behind the seats that’s over the wheel arches .. so there’s storage underneath it ..
given a choice I’d have a rock and roll bed in there but it works for that I need just a pain in the arse with fixed seats in the back because it limits you to what you can put in there
additionally make sure you insulate everywhere and maybe think about a diesel heater .. I did a week in my van when I split with my e