Hiya neighbour.
I think your concern with the cold is quite accurate. I've stayed in my Adventurer at -25C but that was with power. It's supposedly 4-season but the furnace didn't stop much. I've never actually tested it but I'm not sure if I could make it through a night at that temp with my two batteries.
I also have 300w of solar but again I'm kinda useless to you because I haven't been able to test it. I bought this and set it up for that use (for me quadding in the winter) but then my group blew up and plans changed and it never happened :(
