Dual propane tank equalization
Equalizing the tanks is not what you want to do. Instead you should allow one tank to be fully consumed before switching over to the second. This gives you the consumption time of the second tank to get a replacement or refill of the first tank. If you equalized and drew down both tanks to empty then you are out of available fuel until you get both tanks filled or replaced. Also if you were in the habit of keeping spare full tanks available on site the first approach only requires one spare tank while the latter requires two spare tanks.

The method used to switch between the two tanks is something you can choose based upon what tradeoff of price versus convenience works best for you. Obviously the simplest is probably a manual switch over valve.