Our Phoenix Cruiser 2350, the rear corner bed has the inconvenience described two replies earlier. I admit it isn't ideal, but as long as you are nimble in life, it does work okay. Significantly overweight people generally have trouble with a PC-2350.
I sleep on the inside, my wife against the outer wall. If she has to get up to go to the bathroom during the night, I simply get up so she can get out. I'll sit at the dinette until she's done, then I take my turn in the bathroom while she crawls back into bed. We work together to make it work. Though not ideal, it surely is a whole lot better than crawling out of a cab-over bed or setting up and tearing down a couch-bed daily.
Also keep in-mind that some rigs with couch-beds, one person still has to crawl over the other to get to the bathroom.
For most B+ rigs with main floor sleeping, if you want each person to have independent access to the bathroom, you have to add 3 more feet for near 27' to get twin beds with a rear bathroom. Add another few feet to get a walk-around double/queen bed inside a side-protruding slide out which places the bathroom in the middle of the house.
I did see a rear queen couch-bed inside a rear-protruding slide out on a shorter rig, but that is uncommon.
There are some creative ideas with Murphy beds too.
Do your research. You will be surprised what is offered these days.