We have a swivel on our passenger seat (E350, also) and it's a bit of a hassle to use. The space is very tight and you have to slide the seat back and forth, plus fold forward as it goes around. Once done it's OK but reclining is limited. The floor on our rig is flat, but if there is a rise from cab to coach, the seat is not comfortable. On the drivers side, not sure it will turn around due to the steering wheel. When doing the install, allow for the seat belt sensor wiring. Our MH came equipped with the swivel so I can't comment on brand.
Norm