I have been digging through threads about this myself today. It looks like the gorilla is your best bet. You can get them in a 5 (part# 71481NB5)
THE SKINNY on the Gorilla System
Basically what makes these better is that you cannot just go to an auto store and get the key. Each set is unique. The inside and the outside of the lug nut will spin unless the key is in and locks both edges. They give you a sticker, for in the glove box, that has the code if you happen to loose your key to order a new one.
ANOTHER OPTION FOR YOUR SPARE
I find these Heininger Automotive HitchMate® Spare Tire Lock(shown below) to be intriguing also, but they got crap reviews on amazon. It seems if there was a quality product like this it would help deter people from wanting to break into your car to find your lug nut key. I guess if they are that motivated you may well be screwed anyways?
Heininger Automotive HitchMate® Spare Tire Lock
Manufacturer Part No: 6027
also makes something like this but it will not fit over the factory lug nuts. Someone on amazon said they were able to get it to work with a smaller aftermarket lug nut. Shown below
Master Lock 262DAT Chrome Lug Nut Style Spare Tire Lock