-- Last Updated: Feb-05-13 10:47 AM EST --
And park under a light, near the door.
Here is a source for cable locks, there are others that have similar ones. Wrap them around everything in sight to be visually confusing.
Also, just slow the thiefs down with extra straps. Double the straps front and back, both bow and stern tie downs and a couple of cable locks... if it takes them 20 minutes to figure out how to even detach the boats from the racks they'll likely move on.
I am sure you can buy alarm things that will go off if some connection is broken. Or you can just add some objects that will fall down and make a lot of noise if the kayaks are dislodged.
If they are pros looking for certain kayaks, they'll probably get around anything. If it is an opportunity grabs - something that is pretty easy to manage for a lighter boat like the Loon - just making it take time and parking under lights should do it.