I'm not sure if there are safety inspections for the larger trailers here in MO. The largest one we have is a 24 ft aluminum stock trailer. I'm not sure what it weighs but I think it weighs more than 7,500 lbs but we don't have to have it inspected and it also has permanent tags.Safety inspection only on trailers that gross more than 7,500 pounds in Texas.
From TxDMV....
Registration is required for all non-farm trailers operating on public highways.
Depends on the law enforcement in the area, Some officers are sticklers for traffic law enforcement.