I have a rear window in mine, the 29B floor plan made for about 10 years.
Winnebago shows window locations in their
on-line floorplans.I haven't seen both side window and rear window in a corner bed C for a few years. I think rear windows have become "out" because of styling changes in bigger motorhomes (e.g. they tend to put the closet back there now). The little ones mimic what the big ones do.
Rear windows used to be common, I have seen them in older rentals. You may have to look at older model years. Current Access 26QP has a rear window, but it is a foot and a half longer than what you are looking at. F-R's Sunseeker line currently has three models with corner bed and rear window.
You might call Winnebago Specialty Vehicles about custom building something for you.
Tom Test
Itasca Spirit 29B