I have seen here in Germany several trailers with "home made" hard tops, maily with maintanance platoons or units during my time at the German Army, when in contact with the partner units of the US Army. However, 30 years ago I did not take pictures of these trailer. I did not know by that time that I will some day be a member of the MV scene.
Most of these trailers the body was raised to the hight of the towing vehicle. These hard tops mainly where built from playwood and painted in the actual camo colours. The reason simply was to protect the contence of the trailer from sticky fingers.
By the way, also trucks were modified the same way. About 14 years ago I made a Deuce with an Army built playwood body with an interior hight of about 9 feet road legal for Germany.
I also have a picture in a book of a Dodge WC62 with a wooden house body from WWII.
Wolf
Motor vehicle expert, government recognized