broken tab on future fin box

hey everyone,

i have a 3 month old JS fatfish 2, which is an excellent east coast board except for one thing: i was surfing it in some meaty beachbreak and for some reason the white tab in the back of the future fin box on the left rail randomly broke off and sunk to the bottom of the sea. any idea on how to fix this? i was thinking taking a metal dowel, cutting it to the width of the box and just supergluing it in, but i highly doubt this will hold. comments/suggestions much appreciated! ill pretty much try anything to fix it.