Don Casey's book, "100 Fast & Easy Boat Improvements" has an idea you might be intereted in. The book runs about 15 bucks.
Instead of the typical cross hatched grating he recommends slats, fore and aft (length ways). He recommends 1x2 lumber, dimensional ideally. Teak, of course, is the most desirable for durability, but he lists redwood, red cedar, or yellow pine as alternatives.
You cut cross bracing that spans the width of your cockpit, getting as close to the sides as possible. Then you cut length ways pieces to lay on top of those, screwed together with brass screws. if the steering pedestal is in the way, cut the grate in two and make a semi-circular cut out for the pedestal base. Put some rubber or plastic feet on the bottom to lift it ever so much above the deck.
Here's the nice part of the idea. If you fasten some cleat stock, around 1x1 in size, an 1-1/2 to 2 inches below your seats on the sides of the cockpit, you can lift the grate out and lay it across the open cockpit. Resting on the cleat stock, you've now converted your cockpit into a good size bed!
With the types of wood recommended, I'd use epoxy where the slats cross and epoxy the whole thing before painting or varnishing the whole shebang. Although, with the redwood or cedar you could make a case for just staining it. I'm assuming teak is not in the budget, or we wouldn't be having this conversation.
I think casey's book is available at wm or on amazon.
Hey thanks for the book tip. I like the idea of being able to raise it up to make a bed.