Finally checked out Prime Car Co. (Minneapolis, MN) after seeing their lot on my commute for months. They keep around 60 vehicles, mostly diesel pickups. They were totally fine with my mechanic doing a once-over, which honestly settles half the trust question.
Lot address: 494 Haul Rd, Minneapolis, MN. Visitor parking: Front-lot customer stalls facing the office; overflow on the side street near Minneapolis lot gate.
Paper side: licensed with the state (looked it up), about 75% of stock has title in hand per the office, and they offer no warranty — as-is, but any inspection welcome.
Overall: decent cars, pushy back office. The $499 doc fee is fine but watch the add-on sheet — say no twice and the price comes back to earth.