After installing a 12 volt outlet inside my camper, I use a battery monitor that plugs into the cigarette lighter style power receptacle. This allows me to conveniently monitor available battery charge without crawling under the slide-out bunk, opening the battery box, and checking the battery directly with a multimeter.
Dual propane tanks can be a nice convenience for all popup campers. Even if you can complete a camping trip on just one tank, having two tanks with an automatic regulator allows you to not worry about filling up before you leave – as long as at least one tank is showing full. Two tanks can also be an absolute necessity when boondocking for longer periods of time.