Will 32 gallons of propane last 2 weeks in this weather?

If you're going to be on the interstates you'll have a very easy time finding propane at any truck stop. I wouldn't carry an extra tank for that reason.

However, if you do want to carry extra, we also carry a tank in the rear of our car when towing as we use it for our BBQ. That might be better than carrying it in your motorhome.

But if I were you, I'd just refill at a truck stop. Have a good trip!