In search of drier trailers

Do you have electricity at your trailer?
There is a device called Dampp-Chaser that is used inside pianos to
keep them from soaking up humidity. It is a long rod that is heated
electrically and will elevate temperature enough to keep a piano dry
(but not too dry). Two or three of these strategically placed might
do the job. I believe they are available in more than one length.