Leaving Dog in Parked RV

We are considering downsizing to a small C or B+ and not towing a car. In our current setup, if we are leaving for 2 or 3 hours and do not take our small dog, Havanese, with us, we leave the AC set in the rv in case it gets too hot. When we downsize,we may end up with an rv small enough to do some shopping, sightseeing or eating out and may occasionally need to leave the dog in the rv. In warm weather, my plan would be to leave the generator running, with the AC on. I have searched the forums and some people seem to do this with no AC, and just a window open with the roof vent open and fan running. I know that if the outside temperature goes much over 70 degrees, the inside temp of our current rv is reaching high 70's and it is time to put on the ACs. Some places we park may not allow generator use, so no AC!

Is anyone with a pet in a similar situation, and what do you do?