T1 enclosure needed for under seats in my boat

[Shane]

My boat (200 Nordic Heat)doesn't have a lot of space to mount subwoofers. I was thinking of trying to put them under my drop down bolster seats, but recomended box is a few inches too big. Also, which way to face the speaker to keep it as dry as possible.(can't post pics? How do I post) it's really hard to explain without showing it

[Shane]

19.5" h

17.5"w

13" d