I've finally finished the petcock protection, they are separate piece that is glued to the bottom of the tank guard. You can see in the bottom picture that it is still possible to switch to reserve etc with the guard in place.
If you order the Petcock Guard with the Tank Guards I will stick it on there for you. If you've already got a set of Tank Guards it can be purchased separately and you can attach it with the same glue you attached the guards to the tank with.
The price is 22 AUD. Shipping is included with the Tank Guards, if you order it separately shipping will be the same as the Frame Guards, see the first post of this thread.