Seems like a good idea. I don't know the details of the ring but I looked at the picture on Festoolusa.com and was surprised to see that there is a fairly clear enlargement photo of a ring instead of the usual useless grainy blowup of the thumbnail image. Comparing the diameter to the height it looks to me like the projection is only 8mm max. Good news for you! But wait, then I looked at the other rings and realized they used the same photo for four different rings.
You gotta fix stuff like that Shane.
I would think that Festool would have all the specs for things like the copy rings on the website. It would be nice to know the inner diameter of each copy ring as well.