My new Open Range has 4- 20 pound propane tanks. 2 on each side with regulators. I do not see a switch between the two sides so I assume it will draw off both if I left all the tanks in the open position. Right now I am just working one side. My plan is to use the two outside tanks until the regulators say they are empty and switch to inside and fill up the outside tanks. Am I thinking correctly here? The dealer said the law is only 3 tanks can be used and the 4th is an extra. I hooked it up anyway.