The K&N filter (oiled cotton) will not pass water. It will choke out the motor first.
BUT, the adapter the sell for the KTM's in the past sucks, it will pass dirt. Good filter, bad application.
Foam filters let water right in. The con-rods on these bikes are VERY expensive.
Re-think that boat.
"Dad, can I get a motorcycle when I grow up?"
"Son, you can't do both"