Thanks all...
I really don't have any doubt at this point that it was that Suburban. Given the layout of the parking lot and what was parked there that day, it wouldn't make much sense for any of the other vehicles to have done it. I'd park back to back with an early '90s Suburban to prove the point, but I've obsessed enough about this already.
Here's a pic with a slightly downward view of the Suburban bumper and how it lines up including the scuff on the bumperette.
Considering the mass of a Suburban slowly backing into the soft plastic bumper of a 986, I think she may not have felt it happen. ...I hope that she didn't.
I have another matching tail light already. I can do the paint work myself. I plan to get a gallon of Arctic Silver, so that along with the bumper, I'll have enough paint to fix some spots on THAT as well - hood and a rear fender.
