i slept on a cabbie type of thing in a magirus deutz 192M16 lhd drabar in the 80s,the trick was to,open window a little pull curtains ,stand on step(door open lol) fold down bunk and slide onto bunk ,shut door by pulling at window… not good if you had a beer or 3.
if you couldnt be – you just had enough room to sleep behind the seats which was good as it meant somebody could drive while you slept…
will figure out how to scan its picture …FSM 391Y. funny how you can remember reg nos nearly 30yrs ago… 
jimmy…