High temperature alarm for when you're not there but pet is.

Thermostatically controlled vents will NOT keep your pet safe from the heat. The RV will reach dangerously hot levels within minutes after the ac goes off.

That said a smart phone and any one of the inexpensive nanny cams will do the job. nanny cam pointed on a thermometer. View on line with smart phone while you are away.

But again you only have a very limited amount of time to get to your pets if the ac goes off when it is hot outside. Just saying.