Instead of making two stops, drive 65 mph both ways instead of 77mph and you'll save time overall (adds only 10 minutes each way and avoids a lengthy Level 2 charging stop) and improve your Wh/mi. While cold temps reduce range because you have the heater running, speed above 65mph has an impact as well.
Might as well make it 55 mph right? Not a good way to impress the ski buddies, or other traffic on that highway. Besides, Loon is closest and least desirable. Bretton Woods is the real goal, and it doesn't matter how slow you go, just won't make it.