When we have to leave our dog in her playpen in the RV in warm temperatures in a non-hookup situation, we leave with the built-in generator and roof air conditioner running ... while at the same time FOR SAFETY BACKUP (in case the generator should ever quit while we're gone - it did once) ... we also leave a powerful 12 volt fan set on high blowing directly at the dog's playpen. In moderate temperatures we leave the front/rear roof vents open with the front vent's built-in fan drawing air from the rear vent through the full length of the motorhome.
We feel that this is a simple arrangement not relying too much on technology.