I added a swivel to the passenger seat on my Sunseeker 2300 Chevy. Driver's seat would have turned into dinette, so didn't bother. Go to discountvantruck.com. They have a swivel plate that fits between seat base and seat itself. Raises seat height about 3/4 of an inch. Comes with bolts. The swivel lever protrudes between passenger's legs. It was too long, so I cut to size and covered sharp end with a "screw protector" available at Home Depot, etc. The job was very easy. Better with two people just to help with weight of the seat.
The seat swivels with door closed, but requires moving seat on track as rotating. Much easier if door is open. Have used it now for a year and love it.
2012 Forest River Sunseeker 2300 Chevy