So just remove Improved Touring from the GCR and leave it to the various regions to publish their own regs. Problem "solved".
GA
I would really hope you simply forgot to turn on the sarcasm font. If each region can make changes to the IT rule set, having any hope that people will travel outside of their region would be foolish. I doubt I am alone when I say I don't want to have to keep track of several different regions' current rules in order to confirm that when I go to another location my car will still be legal. ITE is that way now. NER has one opinion of what is legal, WDC has a completely different idea and most NER legal cars would not cut it in WDC. I'm sure there are other similar situations, but that is the one I familiar with.
By having the IT rules in the GCR and therefore consistent across the country is one of the appeals to it. You know that you can pick an event and go to it and there will be cars that are similar to yours to race against.