You didn't specify but I assume you are talking about a sailboat, and all of my comments below are addressed to that. If you are talking about a motorboat, then your RV experience is more appropriate and can most likely be directly transfered.
If you are going to use your boat as a liveaboard
at a fixed dock
with occasional daysails, or short term coastal cruising, you can be creative and do what ever works for your comfort and storage
If you plan on any real bluewater cruising, you need to remember that you will NEED comfortable seaberths. You also need a place to sit in comfort on both tacks. A good seaberth is long enough and straight enough to fully stretch out in. Wide enough to rollover, narrow enough to hold you in place and is parralel to the mid line of the boat. and for comfort, they should be as far from the bow and stern as practical. Boats above a certain size can have good sea berths outside of the main cabin
, but for most of us that is where they have to go. A lot of "modern" boats designed for the boat show
and yacht club crowd don't have sea berths any more. But for long offshore
voyages your alternative is to sleep on the cabin sole
As alluded to above, no matter where you stand in the cabin
, you need to be with in arms reach of a good solid handhold no matter which way you fall. Dance floors do NOT make good small boat cabins. Overhead handholds work for us tall people, but if you have a 6'3" overhead clearance, and a 5'1" crew member
it will be a long reach.
You say that your RV bounces on bad roads, but it will never spend hours at a time bounceing while heeled over at 15 to 30 degrees, it's a very different world.
Most of the issues you raise about the comfort of setees can and should be addressable by a good cushion design, especially the angle of the back, and the depth
and height of the seat. For sleeping the back cushions
can always come off.