I agree it's pretty problematic. It could also be disasterous if it were to come apart. I don't go so far as to cork mine. I think the best thing to do might be to cut (ack!) some inspection plates into the storage compartments just behind the fishbox, one near the thru hull and, one near the drain. Mine has one near the thru hull but not at the fishbox drain.
I've just about decided to re-configure my casting platform like the Shaeffer knock off. I have a bow mounted chair now, but it's mounted to the fishbox lid which has delaminated as a result. I like Shaeffer's solution, the fishbox is aft, where it can be larger anyway and, the split lockers are in front with a web between for a fighting chair.