Mold in the chain locker is perhaps a bit of a "chicken-egg" conundrum - vent the locker and don't get mold in the first place. If there is mold, get rid of it and vent to prevent it from forming again.
No need to reconcile yourself to having a sealed "mold holding tank" as your chain locker.
Btw, we periodically "hired" a cruising family's child (7-9 year-olds work well) who fit into the chain locker and could scrub every corner. Also, if you're replacing rotted bow locker floors, that's the ideal time to remediate any old mold and add a vent.
SN68 Sangaris, Tropic Isle Harbor, FL