We have a large compressor dehumidifier we used to use in our motorhome, but it's so heavy and a real pain to get in and out of our coach. I switched to a Davis Air-Dryer 1000 and so far I am very pleased. (Google it, like $60)) These were designed for boat cabins and storage areas. It is actually a very simple little 120v heater unit, with the premise that it keeps the interior temp high enough that condensation doesn't form. It has no fan, no moving parts, and it's small, light and easy to store.
We've used it all summer at Pete's summer site, with the fantastic fans open (with the covers on them) and the A/C set on 90 while we're gone. The little air dryer keeps the interior at about 80+ degrees pretty consistently, even when I first installed it this past winter when we still had some cold nights in central Florida. I even left it plugged in when we camped when it was cold (when you really struggle with condensation in an A/S).
We have no musty smell and although I don't have a readout, the humidity level always feels very low. Worth a look in my opinion.