There's definitely a benefit to using a de-humidifier from time to time but throwing all of the windows and doors open on dry days probably works just as well (as long as you keep an eye out for intruders). The problem is when you leave on a damp cold day having been there for a week or two, you shut up the caravan damp and hope. A couple of £100 dehumidifiers on a time switch might be worth considering but I'm no expert, just trying to help.The problem with these might be over filling if you are not there to empty the collector vessel.
I know quite a few touring caravan owners have a dehumidifier and use it at least at the end of the season before they store the 'van for the winter.
I would ask around your site and speak to the site owner see what they recommend. They might have a dehumidifier that they loan out.
We once had a client make a claim for mold and mildew in a new touring caravan. They had left their caravan with a wet sleeping bag in it when they closed it up for the winter. They had a busy time and didn't return to the caravan for a couple of months. The whole thing was filled with mold and mildew and when they cleaned it off there were little white circles all over the woodwork etc. The insurer didn't pay out because in common with almost all caravan insurance policies damaged caused by mold and mildew is excluded.
I'm telling you this cautionary tale to encourage so that you can learn from the mistake and take steps to protect yourself from something similar. You don't need to be paranoid, you just need to have a plan and do it.
Best wishes
Phil
