I've done it. Here's how.
First off. The connection at the deck does little. One could argue that it secures the top of the plate to keep the rod centered. But the main function of the four little screws is to keep the plate from unscrewing when the boat is in service. The load of the spar is carried by a steel beam inside the hull at the bottom of the inner rod, NOT AT THE DECK. The steel beam is free floating and can never be removed without cutting open the hull from the outside because cutting the inner liner means having to build back the liner glass in the most difficult and critical place of the boat. Forgettaboutit. Any how, back to the chain-plate. To re-bed (assuming you have a leak into the main cabin) the plates with the mast up, rig a preventer to keep the mast where you want it. Remove all shrouds attached to one plate. (Do one side at a time if the mast is up. Don't push your luck) Remove the screws. Get a big wrench and snuggle up to the plate. Treat it like a keel bolt and twist. (counter clockwise) The only thing holding it in place is caulk. After it breaks free, count the number of turns. It helps to know how many during re-install time.The rod you are turning probably won't tell you when it's free so after about ten or so turns, start pulling up on it after each turn so your counting means something. When it is free, remove the old caulk and reinstall with new goo. I used 5200. Mask around the chain-plate on the deck. It helps with cleanup.A trick is to wait to apply caulk around the shaft until the treads start to engage the steel plate of the hull liner. That keeps goo off of the shaft where it isn't needed below.If you want to get fancy, instead of using enough 5200 to reach the interior, just use enough to do the job topside. Then use white silicone to fill around the shaft from below. Looks nicer. Look, this is a lot of verbiage to describe a really simple job. The only thing you are doing is rebeding. Like a hatch. That's all these boats need. They are not like the boats in that article. None of that bad stuff can happen to this design.