How would you bed deck to stringers in preparation for glass (deck already installed)

[Enyar]

My boat appears to have a partially floating deck that is only tied into the stringers in certain areas. I'd like to fully close it in in areas that I can reach to really beef up strength/minimize water intrusion. My console is glassed to the deck and the T-Top is bolted to the top of the console. I think this is a bit of a design flaw and it puts extra stress on the deck that's not supported underneath.

I'd like to fill it with a thick mix of resin, then go back an run a filet / cover with glass. I just don't know how feasible that is working upside down/in tight quarter.

Could I fill with a bead of plexus to act as like a backer rod and then try to run filets?


Sorry for the horrible picture.