there is an onsite camping parking lot where tent people park. If you parked there you could move if you need to. as far as ins/outs from camping I think they are waiting to hear officially from the city if they can do that. It's not normally allowed at other festivals. I have my fingers crossed.
As far as propane outdoor heaters go. .. um.. its not going to get cold so that is a tough question. I dont think you would need a heater in the desert in May. (it will be warm enough to sleep outside in the open).