No help on Drying it out. But I discovered the same problem, water had gotten in to the tail lights and rotted the wood core. I used epoxy resin to repair the damage. This one has a long curing time so it soaked into the wood..
https://smile.amazon.com/gp/product/...?ie=UTF8&psc=1
Once it was dry I seal the entire compartment with Flexlseal..