>>What if you had one of those tent platforms with an actual tent on top of
yer car?
Might have the ole park ranger wondering.......
   
When our kids were younger and still camping with us we would bring a small tent along with us.  It gave us more room in the van.  I wonder if your park ranger would let you stay in the tent area if you put up a tent and then used it for storage.  Some of the small tents are almost as easy to put up as an umbrella and would not take much room to store.
About 8 or 10 years ago there was a guy (Blue Nelson?) travelling all over North America in a coach built VW (a Beuller, spelling?).  He had a small tent mounted to a rack on the roof of the car.  He turned up at the Regina Vee Dub Club annual Show and Shine.  There was also a write up in VW Trends or Hot VW's)
George
'85 Westfalia