if your j box heaters are tight there is no problem with heat i run mine at -20 and stay plenty warm i would like to add a fuel fired heater for when i'm not under way such as ice fishing or sleading the one other plus to the fuel fired heater is dry heat to remove moisture propane wil create moisture as you can see the diference on a boat when yiu ahva a lp heater verses a fuel fired heateralso if you do add a lp heater you must have the fuel bottle outsideso if the releaf vents off it dosn't fill the cab with gas.