Do know that any solution applied to the outside of the liner will eventually loosen. Water pressure from the inside working out will always find an edge to get into. After it gets wet underneath failure is only a matter of time. Solutions from the inside are few. You don't want to put anything that may be toxic to you bait in there.
There is no end of problems with those (or other) foam liners. Way back I came across a hard plastic storage tub (like Tupperware only cheaper) that fit exactly, more or less, inside that foam liner. Problem solved.
Might have to look around a bit, take some measurements and either memorize them or write 'em down. Food service sized containers are a good place to start.