I've done a similar trip from MI the last two winters (escaped early this winter)... I've always left the RV winterized until south of the frost line
Dewinterizing is simple to do when ready - just needs some fresh water of course.
What is in heated space or not varies by rig, and to me just isn't worth the risk... On mine (2014 Hurricane), I'd be most concerned with the drain valve area - my tanks are heated - but not the drain pipe to the gate valves.
As long as I am keeping the rig heated, I could likely carry fresh water - the tank is in cabinet between dining table and bathroom - but I wouldn't run the water pump or flush the lines till far enough south.
If the temp is around 30-32 - I wouldn't be concerned with my setup - the heated rig will be fine... but dropping into the 20's or teens as is likely in MI or upstate NY at this time (lived both places) would make me cautious.
Minor inconvenience to not use the plumbing for the first day or so - compared to a major repair to start my stay in the sunshine state.