Only the first pic still works:
Not really that different than the ones around sprockets, just around the disc instead. The possible plus over having it on the sprocket side is it might reduce chain lube flinging onto the wheel.
From the pic, it seems like it might be a little too high to keep LEO's happy. If it's not lit, that could be another source of trouble... especially if you find an anal LEO following you just looking for an excuse to light you up.
We've got squids around here that mount 'em up in front of the tire... but that's just asking for trouble.