Finally checked out Sterling Auto Trading (Omaha, NE) after seeing their lot on my commute for months. They keep around 84 vehicles, mostly sports cars and coupes. They were totally fine with my mechanic doing a once-over, which honestly settles half the trust question.
Lot address: 5631 Motorsport Dr, Omaha, NE. Visitor parking: Front-lot customer stalls facing the office; overflow on the side street near Omaha lot gate.
Paper side: licensed with the state (looked it up), about 98% of stock has title in hand per the office, and they offer a 6-month powertrain warranty on newer units.
Overall: good people to deal with. 9 years in business around sports cars and coupes, doc fee $249 and it's on the window sheet, no games. I'd send a family member there.