You guys are so isolated from the world of boat theft. It seems odd to take a ski boat but I would lay odds that it was simply somebody filling an order. I will also bet that a truck was stolen for the job.
Down here in the Sunshine State the boat would be found the next day in S. Dade or Homestead stripped and dumped.
The extent some guys go to to safeguard their boats is ridiculous, and often fruitless. I'm talking broad daylight, from behind a locked fence in your own backyard, nosy neighbors and all. Gone. Even waving to your security camera.
Large center consoles with multiple engines and long range are run to Cuba for human cargo then dumped in Isla Majaras. Smaller, fast offshore boats are used in the Bahamas for a drug run or two then cut loose or sunk outright.
There are numerous GPS tracking devises on the market, the thefts have spawned an entire industry of loss prevention.
Like anything else in this world, you can slow down the thieves but you cant stop them. If caught they will do 48 hours, get time served and probation and be stealing another one in less than a week.
10 K a head for as many people as you can fit is a nice payday. Go steal a boat.