Slingo - Many boats have space issues for idea subwoofer location and displacement considerations. Your boat is not one of them. I had the pleasure of tuning Mandleys Mojo yesterday and can say first handed, you could put a few people (literally) in storage compartment and even helm area. You have tons of room for a subwoofer. It's really going to depend ENTIRELY on how carried away you want to get in the process. That boat is big.

I think an installer should have no problem fitting either ported or sealed enclosures in there for you. And still work around the cables you see. Just make sure you elevate the enclosure as to not bind the cables and you'll be good.

8/10/12/15/18" - you got the space.

-Brian