Hi
We have SBT's and they are both house dogs. However, they both sleep in crates in the awning, they aren't allowed in the van.
During the summer, heating is not really an issue. We ensure there are no draughs. We put an eco friendly ground sheet down and put the crates on top of that, side by side. If temperatures do drop, then we cover the crates with a couple of thick horse blankets (clean of course), LOL!
We are just about to start winter caravanning. So, I have bought a Dorema porch awning. I will do the following:
Put ground sheet down
Put thick cardboard over ground sheet where crates will be sited (might even put a couple of camping mats underneath too)
Put dogs bedding in crates
The older dog will wear either a fleece or knitted 'jumper'
We will cover both crates with a horse blanket or two
However, if temperatures drop significantly, then I have bought two single duvets 14.0 tog (I think). I'll put the duvets in the crates for them too so they can scratch about and eventually cover themselves up.
As stated, you jut have to bear in mind that you are taking a house dog out of the house and putting it in a 'tent' and there will obviously be a significant difference in temperatures between a house and awning. Personally I wouldn't have loads of heating on or have them in a warm van because you will then be putting them straight in the awning where there will be a significat drop in temperature.
Not sure if this has helped you or not.
Good luck.
Lisa