[rturriff7]

Here's what I do...

Take a glass of hot water and pour it down the side of the tank from the top. The tank's side will get hot from the water but only where there is no propane. Start feeling the tank at the bottom and it will still be cold (if there is some propane in the tank) and then slide your hand up the tank. When it starts feeling hot, you have found the level of propane inside.

I realize this is not remote but it beats taking the tanks of and shaking them. Hope this helps.