The idea of two type of wheel locks seems reasonable, except that where they are to be broken off, it is more likely to be done by force than by key, so the gain may not be that great.
Trailers that are left for a long while can have a wheel removed, but take care to cober the exposed hub and ensure that the trailer is secure.
The idea of having a busy Marine area is good, the more people you have, the greater the chance there is of having someone who knows who should be around your boat actually seeing someone who should not be. However, "user surveillance" can also lead to high level of annonimity, i.e. intruders get lost in the crowd.
Access control is the way ahead and Marina and yard owners should do all they can to thwart unauthorised access, gates, locks, barriers, passes and a culture of challenge.
Just a few thoughts to get going. You may have guessed that I am "in the securtiy business", I am a Crime Prevention Officer and looking, a earlier stated, to develop a fairly comprehensive advice feature.
Thanks for your note on ob locks, I guessed you would be using such a device and yes the weight alone is a deterrant, my 60 needs at least two to lift and the bigger the engine the more bodies are needed, this probalbly explains why sub 50 HP engines are so ~sought after~!
Yes, I have also heard of transomes being cut out so the cables can be oinced as well. A well placed hard steel strip can be a good deflector.
Don't go looking for bad weather, it will find you soon enough!