Hi Paw Paw,
Heating the basement for most folks is as easy as installing a thermostatically controlled fan.
Folks who have 30 amp service, if they wish to heat in extreme cold, needs must have more than one shore power cord. This is also relatively painless and extremely cost effective. If they choose to not do so, they can dramatically reduce propane costs by running heaters and the furnace.
It is too bad the smallest cheap heat system can be run at the same time as the propane burner in the furnace.
I'm now using "magic carpets" which are electrically heated and do about 85 btu's per square foot. They have really improved the comfort level in my class C, which has an insulated but unheated basement. I don't have every square foot covered but the carpets do radiate heat downwards into that unheated cavity so the floors everywhere are much warmer.
Portable heaters can be a royal pain, but with a little thought they may often be installed in out of the way areas in a manner that leaves no cords to trip over or heaters that tip over.
I did some measurements recently on surface temperatures of heaters, when they were going "flat out". Here they are:
40 c (104 f) "magic carpet"
85 c (185 f) oil filled heater.
135 c (275 f) fan based cube heater
275 c (527 f) pure radiant heater (no fan) quartz tube type
Clearly the oil filled are the safest of the three types of portable heaters. I use 1/2 size ones and those with the carpets are providing a large portion of my heating needs. They total about 2100 watts, and provide a lovely, silent, even heat.
Regards, Don
My ride is a 28 foot Class C, 256 watts solar, 556 amp-hours of Telcom jars, 3000 watt Magnum hybrid inverter, Sola Basic Autoformer, Microair Easy Start.