I am in a much drier climate but,
I seal it up and use a small dehumidifier on a timer to run at night when humidity is highest and condensation is most likely to occur.
I tried the damp rid desiccant. It quickly became a dilute gooey mess. It will only absorb about a cup or two of water per container. I can dump a cup of water a week from my little dehumidifier in a little pop up in a dry climate.
The inside water content will always try to be in equilibrium with the outside and it will come in through all the small air leaks. Once it is inside, it will condense on the cold windows and walls because it cannot get back out quickly. The heater raises inside temperature, lowering the water carrying capacity of the air and reduces condensing, but at a significant energy cost.
Seal it tight. Get a dehumidifier.