Thanks!Welcome to the forum! Lots of info on rear seating here on the forum, not an easy thing to do safely.
So how do I know they’re “safe?” The upfitter’s using Ford Transit take-out seats with the rails, and a Freedman seat plate under the chassis.Not all professional upfitters install seats safely. Seats in the rear of RVs have no safety requirements. It will be upto you to ensure that the install is "safe". There are no standards/requirements for rear seats in a promaster.