Class A Coach with 4 proper seats w/ seatbelts?

quite a few 'A's have 3-seats
a second seat behind the co-pilot, that swvels and has a seatbelt
usually a fold down tablet between them

i'm sitting there right now as i type this

but '4' is a rare thing, you can always buy one with the floor space
remove the oem sofa, install a smaller sofa/love seat ? and add the fourth seat
its not difficult to drill four holes and bolt it down, and two more for the belt anchors