There has been some good advice given here about being cautious, and Bonzothemac is being responsible and cautious. If the RV is parked in a RV park in the shade with windows open and fans running, then that is different than on the asphalt parking lot in the broiling sun. Having said that, I have used two sets of keys for my vehicle, and just left my dog in the truck with the engine running and air conditioning on. Of course, there is an element of risk of theft, but that risk was less than heat stroke if just left in the truck without the A/C.