I just went through this with my LPG company with a gas pool heater (and a rough in for a genset).
I heard the same setback as Trekkie. 10' from everything on the tank (property line, electrical equipment, structures etc). The regulator and gas lines can pretty much be anywhere.
One thing that might be important to know is a LPG system around here is "high pressure" (around 10 PSI) up to the final regulator where it gets dropped to 10 inches of water (WC). That is in the side of my pool heater and not installed yet on the genny rough. That means you can use a smaller line than the "10 WC" designated size. With Natural Gas you still measure to the final regulator but as I remember this is the one where the meter is.
I discussed this with the gas inspector, "book" (what we call 110.3(B)) in hand. He explained the high pressure thing.
