That's about the same as the bed on our Boler
was (45-ish inches). We were able to stretch it out to 48 inches by using an extension that filled the space between the end of the table and the beginning of the kitchen - but the rear bed size played the largest role in our decision to lose the Boler
The PlayPac I gutted and refitted, had a queen-size (60x80) bed in the back by the time I was done with it. Used a residential mattress. Heavy - but very comfy at night!
My long-term plans is to pick up an older 16' Scamp
and gut it out to retrofit a 60" wide bed into the back.
My point of view is that I'm spending at least 8 hours of the day in the bed - so I want that to be as comfortable as possible.