What is your height limit? We had an existing carport when we went looking for a new my and we had to limit our selections. Instead of a Newmar Baystar we went with the Bay Star Sport.
You are correct about the bay's being hard to get to when the slides are out. I've changed my setup procedure to remove the stuff I will need from the bay's before I extend the slides. Doesn't work all the time, but does help. I have the same issue with the non full slides as well.
I think you can find a diesel in the length you want, but the Ford based gassers are just fine.