A lot of folks wish they would put the 54" bed in one of the standard 16'ers (including me!).
It would probably only work in the side bath models, and they would have to make new molds for the galley modules. With
fiberglass, you can't just hack them off. Since the 13' model is their most popular and the 16' side dinette next most popular, there isn't a lot of incentive for them to rework the less-popular side bath model. But I keep hoping.
The deluxe models all have a 54" bed. So if you really want a 54" bed in a 16'er...