I feel the factory should offer an option for a large cab-over bed. Not that I would personally want it, but I think the lack of that extra permanent double bed shys away much potential business for the company. Model 2100 would benefit most from it, but every model would benefit. Few people will mess with conversion beds when there are more than two travelers. Families want to simply send their kids up into a loft at any time of day. It is an out-of-the way hangout place for kids to sleep and play games. Other people might remove the mattress and use it for bulk storage or a place for their pets.
The larger cab-over bed 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.
I would also offer "Easy-Pass-Thru" as an option. Otherwise don't cut the E350/E450 chassis roof for best roll-over protection for the cab occupants. Very few people will utilize easy-pass-thru just to retain the bed at all times. The E350/E450 cab ceiling has decent head room anyway.
That was our experience with easy-pass-thru with our old Toyota based rig shown here. The filler panel was always in-place on trips.