Since you want to use the TC with slides in, I'd go without a slide. In that case, I'd go Northern Lite because they have a couple of more open floor plans.
As long as you have a generator and propane, you can keep topping your batteries off. It think it has more to do with how warm you keep it than the design of the TC. The major loss of heat is in the slides and windows. Obviously, you can keep the slides in on any TC although it may not give you a lot of room and you can make any TC better in the cold by using insulation like Reflectix.
I've used my TC in the Winter with the slides in at night to minimize amount the furnace runs. You'll find a lot of TCs with slides are fine if you close the slides while you are inside even if they are harder to get in without the slide open if you are large.
