Moisheh, traveling recently from California to Florida we ran into the same thing. There was NO room in the normal interstate rest area's for our coach and car. Some of the older rest area's have curb type parking. Since we can't back up (tow car), we have to have room to pull in to a curb side spot and have room to pull forward to get out. You know RV'ers have to go to the bathroom too. LOL!
We also have stopped at the truck stops after fueling to fix lunch in the coach. I'm very conscience of the driver's and try to stay out of their way. I have never noticed a totally full truck stop (T/A, etc.).
Safe travels,
MM.