Finally checked out River Car Co. (Norman, OK) after seeing their lot on my commute for months. They keep around 90 vehicles, mostly import cars. They were totally fine with my mechanic doing a once-over, which honestly settles half the trust question.
Lot address: 2335 Commerce Ave, Norman, OK. Visitor parking: Front-lot customer stalls facing the office; overflow on the side street near Norman lot gate.
Paper side: licensed with the state (looked it up), about 96% of stock has title in hand per the office, and they offer a 3-month/3,000-mile limited warranty.
Overall: good people to deal with. 19 years in business around import cars, doc fee $349 and it's on the window sheet, no games. I'd send a family member there.