I ended up using Flex Seal Tape to try to seal the storage compartment. I cleaned all the old epoxy and duct tape from the inside of the plastic box. I think it is made of some kind of resin, but without any cloth for strength. I aligned the cracked pieces of the bottom to help make the floor one level. Inside the lazarette I put a 20 inch length of 4 inch wide Flex Seal Tape on the outside of the bottom and wrapped it an inch or so up the ends. The 4 inch width is perfect for the depth of the box.
The plastic box is so cracked, even the top surface is compromised. I wrapped a 6 inch piece around the aft lower corner where there is a significant crack at the radius. To strengthen the floor, now that it is held together with the tape, I may use 4200 to put a new floor inside, maybe out of 1/4 inch Starboard.
The tape's sealing side is very sticky and hard to reposition as you apply it. It reminds me of black butyl sealing material, but the sticky stuff doesn't shed itself onto your fingers. That's nice. It has a thin plastic cover to protect the sealing surface while you test fit and cut it to the proper shape. It is non-stick on the back side which makes it easier to smooth out and move the bubbles around. We'll see how it goes, but I like the tape for now. We'll see how long it lasts after it "cures," which can take 24 hours.