Above, you can see how the chainplates come down and are bolted onto a 3/4" thick fiberglass bulkhead that is laminated into the hull. This is incredibly strong. It gives the boat the structural advantages of having the chainplates bolted to the hull (rather than bolted to plywood bulkheads that are tabbed onto the hull). Moving the bulkhead inboard allows the shrouds to be inboard, so you can point higher. What you lose is all that storage space behind the fiberglass!!
At some point I'm going to add hatches to the shelf that's above that space, so I can access it and store stuff in there, like extra sleeping bags and blankets that you want to have aboard but rarely need to pull out.

In the meantime, that 4 inches of space can be made useful!

I took four 14" sections of aluminum beam stock -- .75" x 1.5" -- and stuck on some thin adhesive backed vinyl.
(All from McMaster-Carr.) This is to keep things from rattling and driving me crazy. The beams are hollow!

Then I mounted them on either side, with 7/8" thick blocks of mahogany (anything will do, but I had some scraps.)

I also stuck some adhesive backed vinyl to the back of the fiberglass liner, and on top of the little blocks of wood. I don't want rattles!

On each side, I stuck two 53" long aluminum rails. Originally I was going to use wood, but this aluminum stuff is lighter and stronger. To pull the life vests out, just slide the bar out of the way. I wish I could fit more in there, but at least I can fit three per side.

So my life vests are handy but out of the way, and I have four sections of aluminum beam handy in case I need to jury rig some weird repair someday.

(I have good inflatable vests that I actually wear when sailing...
these are just extras
to make the Coast Guard happy.)