On our old 98 Discovery, we endured this problem until we converted the coach to a 50 amp service. Watch your amp meter, and determine how many amps your ACs draw when they are running. Also try running the ACs on High Cool instead of Auto. This will tend to keep the amp load a little more consistent. Your ACs and inverter should draw around 25 amps based on what our old Discovery drew. If you have your refrigerator and/or water heater on electric, you will most likely being drawing more than 30 amps. Hope thie helps some.
Jim and Lynda, (Sophie, Jake, attack trained killer Shi-Tzus :-))
2003 Fleetwood Expedition 38N 2005 Saturn Vue