Finally checked out Summit Car Lot (Norman, OK) after seeing their lot on my commute for months. They keep around 103 vehicles, mostly pickup trucks and work trucks. They were totally fine with my mechanic doing a once-over, which honestly settles half the trust question.
Lot address: 6063 Industrial Blvd, 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 76% 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. 26 years in business around pickup trucks and work trucks, doc fee $299 and it's on the window sheet, no games. I'd send a family member there.