Sounds like a few good plans there. Love the idea of the enclosed trailer- kind of similar to my eventual plan of a dive van (motor home with minor adjustments for like a tank rack/ hanging for wet gear).
Whatever helps keep your own heat is worth thinking about - I definitely agree with the bathmat or similar. If your feet are warm, it helps a lot with the rest of you. Same with gloves and a hat. Even using a tattered old jacket over a wet (dry or wet) suit to minimise wind chill is worth it.
Even on a warm water dive, I found hot liquid after the dive to be very nice - the liveaboard would provide hot chocolate for the first dive of the day and the night dive with fruit juice for the others. I would have preferred the hot choc for all of them.
The beauty of that little stove is it takes up virtually no room at all so it (and the small gas can it uses) can be packed in the corner of a bag or in the trunk. It is also cheap.
