Rick,
That's a great question especially if you are storing the PA at a location that is not near you. I use on of those heavy duty security cables (can find them in Walmart) that has a loop on each end and the cable is covered in thick clear plastic. I take the cable through the Mirage drive openings on both PAs and route it around the frame of the trailer. I use a 15 foot cable and the secure then ends with a heavy duty lock.
If someone really wanted to take either PA, I'm sure they could find a way to cut the cable or the lock with the right tool. If you have something that goes through the Mirage Drive opening and around the hull, that would be the best option, As far as wrapping it around the PVC, it would be no different.
Keep in mind that kayaks are pretty cheap to get insurance for (either boat or adding them to a homeowner's policy). That would give you good piece of mind. Welcome to the PA family. Post some pictures!