Stan... If you have opportunity to cover your trailer...I suggest that you do such. UV light is the #1 destroyer of the materials that make up our RVs. I have a check list for winterization that I follow. This assures me that I have completed all the steps. I do not have my copy in front of me to share with you but I will offer this video for you to watch.
How to Winterize RV Travel Trailer Water System - YouTube
I wash and possibly wax my rig first
clean interior and add any anti mold and mildew additives I feel necessary
cover furniture with old sheets
MOUSE and Rodent traps
prep water system