Narrower Class C with cabover bunk on Chevy/Ford E chassis?

My two cents is that you would have to increase the over cab height to have any room up there. Narrower chassis and higher bunk do not make for better stability or drivability. Plus, most of those narrow e450 25ft+ class C units sleep 6 without the overhead bunk. The nice thing about those e450 b+ units is they are great to drive. Eliminating the bunk overhang helps in that department.