You need a voltmeter at minimum. Especially in situations where CG are under powered, of which your naked eye will not know. Even though your AC and fridge seem to run OK, you may be causing heat damage to them with low voltage. Heat damage is cumulative. It shortens the life of appliances.
I would suggest
Progressive Industries Power Protection.
I use a Autoformer and a PI. The Autoformer helps shape available power to keep volts up to acceptable levels and the PI will shut down power to the coach for multiple reasons, one of which is volts below 104 which is the point at which damage will start accruing for major applieances.
I also have a Kill-A-Watt always plugged in by the door for my own sanity, since before I had the PI.