I have used a couple of Dryz-Air things in my trailer since 2003 and I have the same TT to this day and it keeps the trailer very dry.
I store at home and have power available, but choose not to keep it powered up running a a light bulb..
I actually did run a light bulb for the first winter I owned the trailer, but that did nothing, except waste electricity and keep it lit up...
I cover my TT as well and I just crack open the roof vents, but don't open any windows.
Works for me in the NW. Where you are, probably have more humidity than I do, so I guess you have to adjust for that as well.
Good luck!
Mitch