DO NOT get rid of the airbox if your worried about water getting into the filters. I've seen more than one motor lock up because they were riding with clamp-ons when it was raining out or the ground had sitting water.
Just get the adapter plate with a K&N and an outerware and your set. Take the lid off for more air and then you'll be running strong. Get the adapter plate from Noss Machine, Dave is a great guy and will give you a discount for being a BHQ member.
Remember, keep the airbox and you won't have to worry about moisture EVER.
Scott
Ive got the adapter plate from nossmachine...its a very nice item.I would recomend it.