Guess I'll have to be the dissenting vote on this. IT is a power/weight class, and IMO if you can't get reasonably close to the listed weight you aren't going to be competitive against the top cars in the class. The 4th gen Camaro is going to have a tough time getting under 3,000 lbs in IT trim, much less 2680 (or even 2815 in ITR). If you just want to beat up on your local IT crew, then yeah, maybe. Our ITS cars here in the DC Region just barely outrun our top ITA cars. But in a strong ITS region (like the SE), or at the ARRC, fuggetaboutit. This is why my '02 is now a track day toy and not an ITR car.
And yeah, sucks about not being able to use the stock wheels. I actually sent a request in a couple of years ago to get that allowance in, but it was shot down.