Couple things...
First, they do check sound throughout the day... you can't just 'fake it' for the sound check.
Second, keeping the car in 'stealth' mode generates too much heat on track and will likely destroy your bumper. This is not my photo, but this is worst case...
I cut off the outer tips on our ZL1 and added V bands so I could make turnouts to direct the sound away from the sound check location. It passes at Arizona Motorsports Park with our otherwise stock exhaust. After the track day, just swap the stock tips back on.
The other option is just lift past the sound check locations, but where's the fun in that?
