When I winterize out TT and/or park it for an extended period between uses, I use Damp-Rid hanging bags and small pails to help keep it dry. I hang a bag in the main part of the TT and open all the cabinets and doors. I put the little pails full of the calcium (what is used to absorb water) in the storage compartments. When using absorbing products like this, CLOSE all the windows and vents - you are not trying to "dry" the outdoors!
Works well for our 21 foot camper. Larger campers may need more things done.
Throw out stuff if it is really nasty with mold, but usually I just clean off mold with something like Chlorox Cleanup (something heavy on the cleaning / bleaching stuff).
