Hellfire,
Keep in mind two things:
(1) the snorkel opening is going to let in a lot of heat and dirt if you don't plug it.
(2) the top is still an opening under the seat even if take the filter out and plug the snorkel opening.
I, for one, have used the extra space for electrical items such as an additional fuse box for the other electrical goodies I've added.
I have considered installing a Seibel airhorn in the space and opening a hole in the front of the airbox, behind the engine block. I'm still considering it at the moment but it certainly seems doable... just the heat/dirt/ water concerns.
Just a thought.