I have a 1250 square foot unfinished basement. One half used as rec area with pool table, dart board, etc. The other half has four atv, boat and various junk. The coldest the basement gets is 55, I would like to put a little heat down there, doesn't have to be 75. Just something to knock off the chill. My initial thought was vent free propane wall heater but have some concern about the safety of that. What is my best option?