I think it would be neat if Phoenix offered an "Optional" large cab-over class C bed to all their models. If they did, I wonder if Irene and I would have considered it. I think the inability to offer that extra permanent double bed pushes families away. Models 2100 & 2400 would benefit most, but every model would benefit some, again as an option to the current B+ cap. It is a nice loft for kids to play games, rest and just hang out in their own space. Other people could remove the mattress and use the area for bulk storage and/or pet bedding.
The larger cab-over bed seamless cap could utilize all other existing body panels so the only unique component would be the front cap itself. That keeps it easy for the factory and cheap for the customer. Tumor it up no higher than the a/c unit to keep the over-all height spec unchanged.
I would also offer "Easy-Pass-Thru" as an option, not standard, to keep the E350/E450 chassis roof unmodified for best roll-over protection for the cab occupants.
Very few people utilize easy-pass-thru anyway. Our old Toyota based rig shown here, the filler panel was always in-place.
Easy-Pass-Thru Open (done only for the picture)
Easy-Pass-Thru Closed (kept this way all the time)