Our 2250 Sunseeker on Chevy chassis has about a 2 1/2 inch step down, so that wouldn't fit your request. That said, I added a swivel to the passenger seat, and while the floor is a bit closer when swiveled, I don't mind. I can stretch my legs out a bit... right into everyone else's way!
Passenger Seat Swivel mod.Perhaps the Mercedes Benz chassis based class Cs have a flat floor at that transition; the only way you'll find out for sure is to walk the lots.
2016 Forest River Sunseeker 2250SLEC Chevrolet 6.0L