Kind of late to the game so to speak, but just read this original thread.

If your RV is equipped with a generator then the most reliable way to ensure your pets safety IMHO is to install a AGS system. My coach came with this system so I am not sure what would be involved but I wouldn't think it would be too expensive to have installed.

You can set the AGS (automatic generator system) to start your generator when your house batteries get down to a certain level and/or when the inside temperature of your RV gets to a certain point.  We don't travel with pets so I keep mine set to come on when my batteries drop to a certain point.

Reviving this thread.  I’ve been looking at quite a few different ones but just settled on the Motorola MC4000.  The feature that I really liked was the fact that it monitors temperature and AC power as well, so even with a total power failure it’s got a battery backup that still allows it to send a message.  I’ve been testing it and everything works as advertised.