I figure my final testing will be at a campground as well. I'll probably gather a crowd too as people realize what is going on LOL. As long as it doesn't end like this, though
Heck with a graphical display you could just draw the tank with a fluid level in it. As long as you are replacing the whole panel you'll want to measure the other tanks as well (and battery voltage and propane level). Going further I'd also add an inside/outside temp to the display (I'm sure you'll have the real estate! LOL).