Not sure but I think that's what Steetsleeper and exwindsurfer have done. Leastways they were talking about doing that. Have a look at the photos Laird put up of the Frog meet, you can see them in action.
Trouble is he has missed the whole idea. I have one on the side of the shed only I used aluminum window stays to hold it in place so I can set it to whatever angle I want. This time of year it is at about 20 degrees off vertical. As the sun starts rising higher during the day I just adjust the angle. Ideally you should be pointing the panel at the sun all day so he could do with the caravan on a turntable.