By "dehumidifier", I assume that we are talking about an appliance which chills the air to the point of condensing water, then puts the heat back in, so the net effect is primarily to dry the air. I use one of these in my house, but not the Boler
I think that the dehumidifier idea makes sense, in the right circumstances. Since the problem is moisture, this is a direct solution. As a side effect which would be beneficial in the winter, the waste heat will slightly warm the trailer interior.
If there is little or no circulation
of air from the outside, the unit would not need to be large, since there is no moisture being created in the trailer while it is stored. A little bit of air circulation seems like a good idea to me, but too much and you're just trying to dehumidify the great outdoors, which seems futile.
Normally dehumidifiers collect water in a removable bucket built into the unit. It is common to have some provision for a drain line
, to allow continuous operation without the need to empty the bucket. The one I use in my house required drilling out a blanked-off threaded port, and screwing on a garden hose fitting.
Even a small dehumidifier is a heavy and bulky item for use with a trailer - I assume it would be a portable unit, used only in storage. Air conditioners dry air, by the same method, as a side effect of cooling; if dehumidification was needed while camping, presumably an air conditioner would be used instead. If moisture is a problem in winter, it might be during non-use times in the summer as well (depending on climate), so I think it might make sense to use it any time the trailer is sitting idle.
The biggest problem I can think of - aside from the power-reset issue - is that at low temperatures the cooling coils will likely form frost
, instead of just condensation; that kills the operation, so winter conditions in a trailer are likely to be unacceptable for dehumidifier operation in many locations, at least without supplemental heat.