Anyone make Dry Storage Hatch Kits?

I got a tandem I want to make into the mothership of day trips and load down with gear. I don;t like dry bags. Anyone know of instructions/kits/whatever for either installing a dry hach…including even sealing the stern bulkhead. Noob.

Don’t like 'em?
Dry bags keep stuff dry. Even in dry hatches. Which, more often than not, aren’t completely dry.

$$$
Unless you just dropped $4000 on a composite tandem, you will never be able to get an absolutely dry hatch. Bulkheads in plastic boats leak. It’s the nature of the material.