November trip and water lines freezing

For the lines to freeze in a living area the temperature inside the RV needs to be below freezing long enough that all the water in those lines get below freezing. That will not happen overnight when the temperature hovers around the low thirties and depending on your RV maybe not for the high 20'. Note this is while your living in the RV and during the day the inside of the RV is warm enough to walk around in shirt sleeves.
I live in N. Virginia so I understand the weather your talking about. If you have concerns about the Mid Atlantic's occasional very cold snaps equip your RV with an oil-less air compressor instead of the less expensive kind. That way you can blow the water lines free of water. Make a run to the dump station before dark then snuggle a warm blanket with a worry free mind. The added advantage is winterizing for putting the RV away at the end of the trip will be partly accomplished.

When liquids freeze, they expand causing the container to crack or rupture. You do take a small risk that water lines and tanks containing liquid could rupture if frozen.

A foot of water in the fresh tank might not hurt the tank if the tank is 18 inches deep (there would be room for expansion). The water lines likely are "PEX" and are almost freeze proof Click Here and read the fifth question and answer.

The biggest problem you face is guessing how cold and how long will the cold last. :@

We did a two week trip in October from our home near the beginning of the Alaska highway down to southern BC, going through some high country on the Banff Jasper highway. Temps were a little below freezing every night but above freezing during the day. We left our furnace on for the coldest nights, otherwise left the vent over the bed open as we don't like it too warm. I did carry pink antifreeze in case the water started to flow poorly. I put a gallon of it right beside the water pump which would have steadily released heat all night and absorbed it during the day. Oh, I think I opened the cupboard doors one night.

One time we were out a little too early and the freshwater drain tap, fully exposed to the outside froze up. I made a point of putting a warm glove over it after that.

Keep an eye on things like how the water flows late at night and early in the morning so you get a feeling for how risky the temperatures are.

It depends on the motorhome design, but generally speaking if it's at all equipped for cold weather use you should have no problem. If the holding tanks and dump valves are exposed underneath with no enclosure, that could be problematic in sub-freezing temperatures. If, on the other hand, they're enclosed and part of the heated envelope of the RV (often there's a little duct going to the enclosure from the furnace), there should be no problem whatsoever provided the RV is kept at a somewhat habitable temperature.

There's no need to prop the bed open for the fresh water tank that's situated on the floor below it. The luan paneling or whatever underneath the bed has very little insulation value; the tank is in the heated space of the RV.