How do you replace a scupper

[jerseyguy]

I have a 1984 V20 Cuddy. The thru the deck fitting to the starboard side scupper has split. As a result the top of the fitting has broken off and the bottom part is being held in place by the hose.

Has anyone replaced one of these fittings?
How did you get access to the clamp holding the hose on to the fitting ( a long extension on a socket drive?).

How did you tighten the nut under the deck when you put a new fitting in?