Rear Bench Conversion

I posted in the wrong place, maybe this will be correct. Have a 16ft Weldbilt and need storage in the rear bench. Going to buy a hatch from FishOn Fabrication and have a local welder install it, so it needs to be sized correctly, cut and welded into the top of bench.

Two or three foot hatch lid, would like to evacuate the foam entirely so there is storage all the way across.

Is it foam blocks or pellet flotation? The aft deck may be pellet I think because pieces migrate into the floor, maybe that's just pieces breaking off?

How can the entire bench be enclosed (dry stow)? It may not be possible without cutting the entire lid. Maybe put a piece of thick hard foam in the bottom?

Want it to lock and drain, can that be done without a lip? And will it have to be braced on the interior of the bench?

Had an 1872 boat and shop cut the entire way across, broke the top with a lip and lined it with metal, more of a job for back yard mechanic.

Look at the G3 1448 pictures I posted earlier today, that will give you an idea of whats under the bench. Its solid foam block.

FYI....I purchased a Cabelas hatch and it was half the price of FOF. They are made by R&R and are really nice.

Be careful how much foam you remove. You may need it some day.

I put a truck tool box in my rear bench seat. Lockable that way and dry storage too.