I understand it is not what you asked for, but have you considered a coffin box? Extra seating, extra storage, you could put a decent sized cooler in there for smaller fish or use it all for bigger fish, without putting water below your deck. Nice ones are expensive, but would be worth it (to me) since you can still get to the gunwales all around.
The biggest frigid rigid is like 6 feet long and 30 something inches wide...and 6 grand. BUT, it is a part of the boat, down to gelcoat and stainless hinges. They can spray a matching gel coat, I think.
This is one of their setback coolers that allow full opening while mounted against a bulkhead. Different monster, but added to demonstrate the possibilities.
One of my fantasy boats is a 23SE with a FR coffin box up front. Extra storage but still full access to gunwales. The new ones just waste too much space with that goofy seat over nothing but floor.
View attachment 40713