If the floor heating proves to be too complicated maybe I just need to simplify things a bit, do you think you would have settled for less radiators doing this over? I was thinking one next to the bed, towel bathroom radiator and one in the elevated seating floor like in the picture below... also floor heating adds 16mm too (for the very low profile kits), it does not seem like much but I am keeping the inside height at 200cm and I am 194cm so it adds up.. I am hoping to truck's height will be around 350cm or lower.. Not easy to achieve with a 4 point subframe, solar, bush rails and suspension lift I am finding out..Insulation is the key.
I put loads of thought into Raditors behind seat backs, 7 program timers day timers, room thermostats and tank thermostats etc.
The reality is that we have never really used any if it to its full ability.
Because we have good insulation we rarely use the heating. If its needed we simply turn it on for about 20 minutes by which time we are probably sitting in our underwear. It will then stay hot all night.
We don't have duvets or heavy bedding, we simply sleep under a very thin fleece sheet and have never been cold.
I have 2 matrix fan heaters and several finned radiators. If I was fitting it again today I wouldn't bother with the radiators and just go with the matrix fan heaters , they put out more than enough.
The lowest we have been is minus 25 at 5000m and it has all performed fine and the inside tempreture overnight was perfect.
What can mess these heaters about is poor diesel , such as Bolivian, but that's whole different issue