Typical good seating has about 3-5 deg slope to the seat, and 20 degrees slope to the back. Typical camper dinette is 0 and 90. They are forced to do it so that the cushions can double as a mattress on the occasion when the dinette is converted to a bed. An occasion that never happens in our (and I suspect, many) campers.
The aforementioned BF 5th wheel had a huge U shaped dinette across the back, with picture windows on 3 sides. We never used the back of the U, and ended up taking the cushion off of it leaving it at home, used the seat for storage.
