Nacra 5.2 shroud tang loose

I have about a quarter inch of back and forth movement on both shroud tangs on my new to me, old boat. The former owner tried to shoot silicon in there to keep water out; it didn't stay. I read Jake Kohl's post regarding a bow tang on a N 20, and he explained how the Nacra shroud tang is installed. I know I can get to the tang from the inspection port in the hull, but not with any type of grinder. Is the best route to cut a hole opposite the tang on the inside of the hull?

I will be allowing the hull to dry out well over our low humidity winter, but I want to open up as much glass as I need to now for max drying.

Thanks for your help.

Do you have a foam core 5.2?

On my 5.2 the shroud tangs are just riveted in place. I would have thought that the best way to make them solid again would be to drill one rivet, replace it with a new one, and repeat until all rivets are replaced...

That's exactly what I did.