RV Parking is available at Circus Circus, but camping is not permitted.  If you are travelling to the reunion in an RV, and would like to camp instead of staying in the hotel, there are several private RV parks in the area.  Below is a list of a few of the top rated places from the  Good Sam Web Site.  For a more detailed description of the sites below, or to see more locations,  go to http://www.goodsamclub.com/

Bordertown Casino and RV Park

(800) 218-9339

http://www.bordertowncasinorv.com/rv_resort/ 

Sparks Marina RV Park

(775) 851-8888

http://www.sparksmarinarvpark.com/ 

RV Park at the Grand Sierra Resort

 (800)-258-7366

http://www.grandsierraresort.com/amenities/rv-park/

If you are going to camp out in your RV, you need only to pay the Reunion Registration fee of $25.00 per person, optional tour fees, and the Circus Circus Banquet Fee of $52.00 per person. 

I have never stayed at any of these RV Parks, but each of these had ratings of 7.5 or above on the Good Sam Site.