Will water lines freeze?

are all pipes/tanks inside the heated area?
bumpy

The tanks are on the underbody, which is not heated. I’m not really worried about the tanks though because of the volume and small amount of time exposed to low temps.

Depends on how you're heating the camper. If you're using the furnace and the lines are all in an enclosed underbelly, you should be good. If you're using space heaters/fireplace for heating, that heat will NOT go under the trailer. Remember to leave your cabinet doors open below sinks either way.

Thanks for the advice!

WIthout an enclosed underbelly I wouldn’t chance it.

2 days and it's already winterized...I'd probably leave it winterized until you are clear of freezing (or at least lows in the upper 20's with heat on at night).

That said, it's probably going to be OK. I would try to keep the waste tanks empty at night and the fresh full. What pipes are not in the cabinets? Usually the line from the fresh water goes directly into the interior and then pipes are run in the back of cabinets.

PS: consider running the hot water heater at night.

I would not leave the fresh tank full. leave a little room for expansion.
bumpy

Why haul all of that weight 1200 +/- miles? I would never trust weather forecasts to be that accurate. If the forecast is off by 10 degrees, your pipes can easily freeze up. I would drain the fresh tank and blow the lines out with air. Fill. your water tank when you get to camp.

“Why haul all of that weight 1200 +/- miles?”

Because you never know, Baraboo.