In reality, I think that one has to think "motorcycle security" and act accordingly.
Yes, someone could snatch the front wheels, but really, they're 19 inches and not meant for motorcycles, so who cares about them?
If someone goes to the trouble of snatching the front wheels, it would be much easier to drag the whole thing up on something and drive away with it on the back, like they do with motorcycles.
Some nice wires, some nice straps, and hide what you can hide should do just fine in every day scenarios. Get an ugly, dark full cover for the thing for leaving it out during the night in dodgy places and a wire lock or chain to lock it to something.
