We're not done for the season and plan to go out again 1-2 times in November and December. If we are not actively using the MH we take it out once a month for a 25 mile drive and run the generator with load for 1 hour.
I recommend against storing the motorhome with vents open. That will insure that the motorhome interior humidity is equal to the outside humidity, which in the winter is quite high on average and is 100% when fog is present. Instead close up the motorhome tight and add some type of dehumidifier either passive or active.
Active is optimal, such as a 50 pint/day dehumidifier. You can set the humidity level to 55-60% and empty it periodically. These dehumidifiers operate down to 42F and do generate some heat since they consume 400 - 600W. We use a unit like this when going to high humidity areas such as the beach or snow country in the winter and we get no condensation inside the windows.
Passive dehumidifiers such as Dry-Z-Air or Eva-Dry also help. We use to use Dry-Z-Air but the crystals are calcium chloride and is corrosive to metal and leather so requires care in handling. Now using multiple Eva-dry units and they hold the interior humidity to 70%. We leave all drawers, cupboards, freezer, fridge, etc. ajar
