Final update on this one: Got the whole setup together and it got its first couple of uses this past weekend. Photos are of the setup assembled and then one of it in use.
All seems good and solid so far, with the post bolted down with 1/2" bolts through the pulpit and deck. The reinforced section of deck is 3" thick at the aft bolts, the forward ones go through the gunwale so it's about 3.5" thick there. On the underside of that whole area is a 4 square foot piece of G10 epoxied to the deck as a backing plate, covering all of the pulpit bolts, windlass bolts and samson post bolts. Basically, it's not going anywhere unless I manage to rip a very large chunk of deck off the boat.