The heating season is here so I'm posting what I did for electric heating in our TT as shown in the photos below.
I installed a 1,000 watt kick space heater (aka toe space heater) under our range in the kitchen/living space. Perfect fit as it's exact same width of the range & door. Installed a King pic-a-watt heater in the bathroom (set at 250 watts) and bedroom (set at 500 watts). The cabinet space under the bathroom vanity was a dead space so easy to install there. The heater above the bed required a box to be made up to enclose the heater inside the cabinet. The King heaters have a squirrel cage blower which is much quieter than a propeller blade style. Total heating load is 1750 watts.
The heaters are VERY quiet. We can watch TV no problem and don't have to crank the volume way up like when the furnace is running. The heater in the bedroom is so quiet, it does not disturb sleep. The bathroom is always nice and toasty warm when having a shower or using the toilet in the middle of the night. The heaters provide very even heating from one end of our TT to the other. All 3 heaters have the required safety clearances.
To prevent the heating load from tripping the 30 amp service, I made up a control unit using an adjustable current sensing relay and I ran all 120 volt branch circuit wires through the sensor's doughnut. If a coffee maker, toaster, hair dryer, etc. are plugged in and/or the converter are drawing more than the preset current (set to about 15 amps), the relay instantaneously disconnects the heating circuit until the load drops below 15 amps. I installed low voltage thermostats and the control box houses the LV transformer and relays.
To prevent the heaters from unintentionally running at home when parked, I installed a latching relay in the control box. Each time we plug into a pedestal you have to hit a momentary contact pushbutton on the wall. Once the shore power is turned off, the relay drops out and will not allow the heaters to run again until the pushbutton is used the next time the TT is plugged in.
All of the 120 volt and low voltage wiring was run 100% concealed in the walls. I removed ceiling lights, AC vents along with AC unit, skylight and fan trims for access points to the ceiling cavity. Then used a fish tape and leap-frogged from access point to access point. I used existing holes in the top plates of walls to get wire down to the thermostats.
The factory wiring job behind the converter under the dinette seat was a rat's nest (typical factory stuff). I had to rework it all to make space for the control box. In the process, I found some VERY crappy splices done by the factory and one wire connecting to a breaker in the panel was completely loose. Many of the low voltage wires terminated in the converter panel had a lot of strands not into the screw terminal, and as few as 50%.
I installed the heating at the beginning of the season. It has worked flawlessly. Didn't include a photo of the momentary contact switch (residential garburetor sw.) , but it has a couple of Blue Sea LED lights I mounted on the cover plate - one "system on" and the other "heaters de-energized". It's fun to plug something in like a hairdryer and watch the indicator LED tell you that the heaters are temporarily off. The heaters have kept the TT warm enough during cold temps. outside that we have not used the furnace once this season. When in Reno recently, the AC would run automatically during the day and the elec. heaters would run automatically at night when the outdoor temp. dropped overnight.
We don't camp in cold temps. so don't need to worry about piping or tanks freezing and would just revert to using the furnace if we did. The electric heating isn't quite enough when the outdoor temp. gets down to around something like 35F as the insulation isn't as good as it could be plus the fact you need to keep vents open to get fresh air inside.