Rather than pour slabs, with the price of concrete these days, you might want to look into 16x16 concrete "stepping stones" at the home store. They are about 5 bucks each and you can back the camper where you want it; pull forward 16 inches or so; slide the concrete blocks under the wheels and back up onto them. You could also make a "slab" out of them by using a substrate of "rock fines" and set the stones on the substrate. Buy a sack of "resin sand"; sweep it into the cracks; spray with water; and when it sets the seams will be "weed proof" but still "temporary."
Slabs here need permits, but the above solution is "temporary" and no permit or approval is required.
Lou and Laura with Bella - German Short Hair Pointer
2008 GMC Sierra 2500HD Crewcab SB Allison Duramax
2010 Flagstaff 8526RLWS - Superglide 3300
HAM CALLSIGN - KC3FFW