sounds to me like:

make the hockey puck

glue in the ubolt

drill a hole in the deck

Poke a string from that hole thru the bulkhead access

Secure the hockeypuck to the string by tying into the ubolt

pull the hockey puck into the boat and up to where it should fit.

loosen the string enough so you can reach into the hole and poke some glue on the edges of the hockey puck as it hangs just under the opening

pull tight on the string to hold the puck in place while the glue sets up.

pgj