[Msquared]

I've been keeping toe at 0, both front and rear, on my SS 1LE. I would get as much negative camber as possible front and rear, and wear won't be too bad with zero toe. In the rear, you are limited on camber by the length of the toe link: at a certain point, dialing in any more camber will force toe out that can't be adjusted out, so you set as much camber as you can while holding on to zero toe. At the front, just move the knuckle in on the strut as much as possible - there is plenty of range for toe adjustment.

Too bad about the 20" wheels. The tires to be on now for a Camaro are pretty clearly the Falken RT660, but they don't make any 20" sizes yet. There's probably more than a 1/2-second difference between those and the SC3s, maybe even a whole second. It's not subtle.

The only other thing you could consider for Street class is an aftermarket set of dampers (struts and shocks). Everything out there seems to be set up with coilovers in mind, which you can't use in Street. But maybe a call to Vorshlag or Strano could get you some good dampers that retain the stock springs? I don't know for sure, though.