Holiday Rambler did make a model with rear bedroom/chairs and desk and also a model that has a neat rear private full bathroom. I don't know if they still do - but you can go to their website and explore the floor plans (I think it was a gas unit).
Yes, the Trek from Safari does have a rear living area motorhome. But it is the one that has no bedroom, but uses what they call their "Electro Magic" bed that lowers down from the ceiling.