Yeh i did the same...... got the R & S series plates, as thats what i thought of getting for the same reasons, and your gonna have to get a list of what you want, in prefrence and go into Transport SA and go down the list until the first one is available!
On the idea front, like you have already done, go with the SKY, RBT, RBB, and obviously keep the numbers 034 or 340, you get the picture!