Couple of suggestions. I have no idea if they'll work.
-Find the industrial section of whatever town you're in and just park there. It's practically an American tradition. I often see campers and vans parked in these areas because they're usually deserted at night.
http://www.sfweekly.com/sanfrancisco/ne ... id=4295002-snip-
"Since citations must be hand-delivered rather than tucked under a windshield wiper, camper dwellers simply refuse to answer their doors, according to the San Francisco Municipal Transportation Agency's Andy Thornley." [That's SF. I don't know about other cities.]
-Park in 24 hour grocery store parking lots and just sleep there. You might not get noticed at all.
- Drive to a Motel 6 or some other cheap motel and offer the clerk $10 to park in their lot and sleep.
-Park in a quiet neighborhood along a long curb away from the yards of houses.
-Flying J Truck Stops or other truck stops. FInd out their locations. I suspect you might be able to get away with sleeping in the parking area of one. I'd probably avoid the wildlife at truck stops.
http://getshowerpower.com/#whereGood luck.