Before I bought our TM I researched how to keep mattresses dry while winter camping and there are many systems that can be used under the mattresses. I'm going try a Den-Dry RV and Boat Under Mattress pad from Amazon.
What have you found to work?
We're in Canada where it's not always the warmest so this will be something we'll have to contend with on a regular basis if we want to extend our camping season into the late fall & early spring.
I can't wait to see your solutions!