We parked free in the back lot, which is free and open. My husband had the trailer for his dirt bike and was given a notice when we returned from walking the strip, he had to leave ASAP because he wasn't in the oversized lot. That lot is $20 for oversized vehicles and free for vehicles that fit in a normal parking space. We left the notice on the windshield and left the next morning. We had no issues the rest of the night.

We parked in Circus Circus's free self parking lot during the day while we walked the strip, and then ended up staying the night there. Relatively quiet (just have ear plugs handy!), and no one bothered us. Parking lot has high enough clearance for any type of camper van or RV.