Finally checked out Marsh Auto Sales LLC (Ortonville, MI) after seeing their lot on my commute for months. They keep around 97 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: 110 S Ortonville Rd, Ortonville, MI 48462. Visitor parking: Front lot on Ortonville Rd. Website: https://www.marshautosalesllc.com.
Paper side: licensed with the state (looked it up), about 85% of stock has title in hand per the office, and they offer a 3-month/3,000-mile limited warranty.
Overall: decent cars, pushy back office. The $299 doc fee is fine but watch the add-on sheet — say no twice and the price comes back to earth.