On a former boat where the hull linings had mildewed badly, I finally
replaced the fabric after trying everything. Fortunately my new boat
is lined in plastic so no odor. However my van and other car suffered
from serious mildew odors which were causing allergy reactions and I
bought an ozonator which removed the odor. High levels of ozone can be
dangerous but you can run the unit for an hour or so at high levels,
then make sure you vent the area before inhaling any remaining ozone.
Hotels use ozonators to get rid of odors like smoke, vomit, etc. but
not with people in the room. I bought mine new on ebay for half the
regular price. good luck