I read this forum all the time but have yet to really contribute. Their has been quite a bit of discussion regarding an alternative to using the propane heater while staying at a campsite with hookups. I too have used a portable electric cube heater in the past but always hate the fact that it's sitting on the floor to trip over all the time.
My solution was to buy one of the small bathroom heaters that fit in a standard 2x4 wall and install it permanently in my 17B Escape. I installed it in the cupboard under the fridge. After taking off the door I filled in the opening with 1/2 plywood that had cutouts for the heater and a switch. After installing the heater I superimposed a scrap piece of oak panelling that I picked up from the Escape factory over the whole area to finish it off ( thanks Reace ). I threaded 14/3 cab wire up through the fibreglass door jamb and into the upper cabinet where I plugged the heater into the plug for the microwave (I don't use a microwave when camping) as this plug is on it's own circuit so I won't blow the fuse if the heater is on while making toast in the morning. I then installed a thermostat in the upper cabinet next to the thermostat for the propane heater.
If you get one of these heaters you have to make sure it is a 110/120 volt one as most are 220/240. The particular one I got I picked up for under $100 from Friesen Electric in Abbotsford BC. It has two 500 watt elements in it. I wired one of the elements through a switch so that I can switch the heater from 500 watts and 1000 watts as needed.
Here are links to King Heaters in Seattle who make these heaters if anyone is interested. They also make a heater like this that is made for RV's and can be switched between 250 and 1500 watts as needed; I've attached that link as well as a couple of images of the install.