I'd go with a permanent deckbeam located in front of the cockpit coaming. It would provide a secure mount for the coaming, an atachment area for your deck strips, and give a good cross bracing to the boat, regardless of the strength of the design and construction of your deck.

I'd do a bulkhead behind the cockpit coaming for the same strength and attachment reasons, and also to seal off the aft area for storage and flotation. I'd put a large hatch in this bulkhead, either a commercially made plastic screw-in type, or a home made plywood and gasket hatch.

I'd do a bulkhead in front of the footrests to seal off the bow area for stroage and flotation. A pinhole size vent in this might be nice, but depending on how big your cockpit opening is, it might not be very convenient to use a hatch in this bulkhead, so why bother putting one there?

Preshaping the tops of the bulkheads, and installing them before the deck planks, gives you the advantage of forms, and you don't have to come back later to remove them.

Depending on the length of the sood strips you are using, you may want to add a temporary (or permanent) beam between the bulkheads and the ends. Similarly, you may want to glue in a small cleat at each end -- just a scrap of wood -- to support the ends fo the strips as you install them.

The permanent deckbeam and the two bulkheads are going to be a minor, but necessary, weight addition to the boat. The additional deckbeams, if allowed to remain, will add trivial ounces in weight. I wouldn't bother removing them for a weight issue. However, they may be impediments when glassing the inside of the deck. If so, yank them and you'll have a flatter work area without the hump of that deckbeam. You can attach those deckbeams so they can be easily removed by using a single staple to hold them in place. Space the stapler 1/8th inch from the parts by shoving a couple sheets of cardboard under it, just back from where the staple comes out. That leaves the staple with a big open bend you can jab a screwdriver into when you want to release the deckbeam.

Hope this helps.

PGJ