Fuzz, As David said above. Also with aluminum hats, it make more sense (to me) that they are placed between the hub and wheel.
I agree that the likelihood of rear rotor maintenance or replacement is low, it's nice to know it can be done much easier. Stuff happens.
Our rear weight biased, fat rear tire cars use more rear braking then their counterparts, but it's still relatively light with normal street driving. Track use is a different animal.
Either method can work. What's more important is that your upgraded kit is designed and sized correctly. Changing any aspect (or parts) of your brake system can (will) affect the brake balance. The change in balance can be positive or negative or diabolical.
To add to what Boss said above, the threads being exposed beyond the lug nuts rule is in place primarily for the techs to be able to do a quick visual. You would be surprised to see some of the weird stuff people do at the track.