Problem with dehumidifier is it will not only work to clear up room, but shoot your evaporation up and is a lot of power. An actual ERV type air exchanger minimizes the loss of heat/cool air when outside is different than inside. (IE not freeze the house like an open window would.) If you were to say just create an outflow, I guess you can have issues with air pressure and such is why even if not a true erv you should allow for 2 way air exchange.
In my situation which hasn't happened yet. I'm looking at ERV type deal, or possibly making sure my ac/heat is drawing air from that room, or just trying to button up the sump room a bit more and running skimmer air line outside.
Part of me was also wondering, what about a more passive dessicant. Literally a ton of those little packets or even just trays of rice. Once they start to get some absorbtion going, scoop them up to go dry in the sun and repeat?