You can but may not be legal, or that good of an idea. I have seen it done, but a outbord motor may be best way. You can make the bike a inbord motor on a shaft drive. You brace the bike in the back run chain from the frunt sprocket to a prop shaft with a sprocket welded to it. here are some that have. 14' ski boat to convert to inboard w/Motorcycle power - Boat Design Forums

Some vids of someone that did Motorcycle Powered Boat

Some things to think about you will be crossing 100 miles of open ocean in this thing at a a slow speed and there is little help along the way. You will also need to cool the motor down as the KLR needs air moving to do the cooling and there will be little air moving to cool it.
If all you want to do is get around it hire a boat or fly over. If you want to do this on your boat get an outbord for it.

Just looked at the boat of yours looks like it will do you can replum the water cooler and run it on the outside of the boat with longer hose or use ice chest and pump water in and out of that. Look out for rust and running salt water in your bike is not a good idea. A DC fan will also work but you will need a doner out of a car for that may want to use a jumper car battery as well, no need for lights so your bike may have the out put for that. You may want a bigger prop to drive the boat and a good size rudder. Just take a video and pics and post befor you go I want to see this thing run hehe.