I do need a 12 volt heating pad because I park in illegal places so the noise of a fueled heater is unacceptable. When I use the remote start that also runs the vehicle powered inverter which is set to power the 750 watt electric heater that is in back of the van under the bed platform. Get heat from dash vents and the electric heater. The remote start run time is too short at 10 minutes. Hopefully tomorrow Ford will change the run time to 15 minutes. I have found the information on how to do that.You really don't need a heating pad , your body puts out heat , three layers of cloths and then crawl in a sleeping bag and close it up completely , it's very important to close it up completely ! , wait 5 thru 10 minutes and you'd be warm even with a negative 30 degree Fahrenheit outside temp.
A problem will arise if you need to get up to go pee because anytime you even open up that sleeping bag slightly you'll get a extreme nasty miserably cold draft .
I used to turn the van on by remote start and get heat coming out of the rear heater core and fan , that takes too long so now I have a Plannar 44d heater that has a adjustable output and the highest setting puts out about 13500 btus , I crank that full blast and within 5 minutes I can crawl out of bed and go pee staying in front of the heater , when done peeing I crawl into the sleeping bag and turn the heater off or onto the lowest setting which trickles heat to near my battery , you could also plug a Hvac tube on to the output of the heater and then run the other end into your sleeping bag if you wanted too on one of those super cold nights were it could get down to around negative 40 degrees Fahrenheit, that type of weather that makes it seem like your walls disappeared.
The remote start comes in handy for warming up the van and getting the cab area warm so when I start to drive the vents are already blowing warm air but I do have to wait for around 15 minutes.
As far as electric heat?? I would forget about that unless you have access to shore power.
Electric heat and electric off grid cooking puts to much of a dent in your batteries.
Imo , I would only use a Mr buddy heater in a emergency or have around for a temporary backup , when I say temporary I'm talking 2--3 days max , I say this because they put out a lot of water.
I do not get fully out of bed to pee. Just get on by side and pee into a old Quik chocolate wide mouth container. Container below bed platform.
We agree on electric heat if used to heat the whole van. A 12 volt DC heating pad only heats the person. The power used is offset by the less frequent cycling of the refrigerator. Pad is quiet and refrigerator is quieter when it does not run. Do not use electric cooking other than the microwave to warm cold food. Micro wave use is for short times.