Thanks, Eric. We've been methodically searching the apartment since yesterday afternoon, with no luck. We've contacted our friends on the playa already to see if the gate can check our IDs and confirmation numbers to show that we're legit and haven't sold our tickets. It seems the infrastructure is there, but I'm told there's no system in place for that kind of thing, despite all the anti-counterfeit measures. (P.S. if anyone knows differently, please let us know!)
If our tickets are still here (and yes, we think they might be, too) we're coming to terms with the idea that we won't find them before our caravan leaves, and leaving without tickets and no exit strategy feels risky. I will check into the postings on Reno CL now, though. Thanks so much for the help, and have a great burn.