fill it, then leave it. just in case.
also depending on the quality of your gas. you should close the tank valve(s). disconnect the fitting at the end of the hose that connects to the black steel pipe that leads to the underside of your r.v.
lower the front of your trailer to drain any oil residue from the pipe. drain the oil residue from the hose(s) as well.
if you happen to have more than a film of oil you may have issues of not having good gas flow during low temperatures.
*** this doesn't address the tanks freezing up during cold weather.
on my last r.v. i installed a 'T' flare fitting between the gas tank hose and the metal gas pipe. i used a flare cap on the 'T'. then in the fall, i would close the propane tank(s) valve and remove the flare cap, drain the lines. (i was full timing).