Been using the baseboard heater for years from back when Interterm built them now build by Cabet. There is a permanent style and a portable heater. They come in three different lengths and watts, and two colors. They travel easy and do supply a steady supply of heat.
I have three that are used to heat my camper. They may not work that well for the full timers who travel lots, but I work construction and find they to work well for me. You will need to turn one off when the microwave is in use. As we all know the gas heat will need to be used to help heat the under belly plumbing. But, in my camper all plumbing is wrapped and has heat tape on the pipes.
Link to the Cabet heaters
http://www.cadetco.com/show_product.php?prodid=1011