This is a little idea, but I'm recessing the cockpit on surfyak so here's how I am thinking of doing it. (Now that I know how to post dwgs you're gonna get bored!):

Now I have 'decorative' strips around the cockpit that I don't want to round over too much when I am sanding so I've added a rebate in the downturn. So that would be optional in most cases. The rebate will have to be rounded a bit with a flat file to fit the cockpit curvature. Also one should keep in mind that the downturn should reduce to nothing at the lowest point in order for the recess to drain. ( You don't want the sprayskirt to be frozen in place in subzero temps!) Some kayaks use a hole instead if you want to keep a deep recess all around - just protect the bare wood well.

The process is to cut up a bunch of 1" plus ( reducing to say 1/2") downturns and glue them to the rim. (say hot glue and carpenters glue in between - I'll prob. use carpenters glue for both). Then plane or sand the bottom of the downturn to the recess profile you want, but carefully reducing to zero at the low pt.

Then the rest of the procedure is as with the guillemot process but you don't have to worry about fitting the base - let it overhang and plane it off when you turn the deck upside down. I've shown a suggestion for glass layup but look at say Nicks book for the proven process.

I've also included another quick sketch showing a quicker and simpler way. see schematic 2