We had this problem with our old trailer (2011) which we just traded in for a new 2014 Jayco 266 RKS with the climate package. I don't know how this will be on the new one yet we haven't had a chance to use it this fall.
In the other trailer we did seem to have the condensation on the windows problem when we get up in the mornings when we are camping in the spring and fall. We do a lot of camping during this time. I usually just get a paper towel and wipe all the windows and crack a window a little. But the idea of a small dehumidifier sounds good - depends on how small it is. I'll have to check that out.