I would keep it in the trunk inaprotective caseand leave it charged and un-primed. Then transfer it to the unheated garage or leave it in the unheated trunk until the end of the season or hopefully after you shoot your deer.

Or discharge it and place it in the trunk and take it home. It will be fine for only two hours. I think it would be fine inside the vehicle for a couple of hours. Just clean it first thing when you get home. If you place it away from the heater in a case, it will not warm up that much.

If need to clean it before you leave the field after discharging it, a 50/50 mix of 99% isopropyl alcohol & windex or justthe alcoholand patcheswill get it clean enough to get home. Run an oiled patch before you leave the field.

Tahquamenon