As for the issue of access to either the the camper or bunking area then there are options one probably not mentioned. As for sleeping I use a hammock...have been sleeping in a hammock full time for a couple of years for a number of reasons...knees were prominent in your thread, and for that I've had arthritic knees for 20 # years and have been able to live without pain for that time using specific exercises as well as being able to do all of the things healthy people do. So for that don't shy away from a truck camper if it fits your needs otherwise.