I keep my van on the Driveway as I drive it all year round - not daily, but probably at least once a week to nip upto the shops or whatever.
Interesting comments here... seems most people keep a power lead to their MH and keep a heater running inside over winter. I've never done that and never noticed any damp or mould, but maybe I should put a heater on frost protect? and in the living space, or in the garage where the water pump is (it is below zero overnight for a significant part of the winter where I am)