I generally specify on the drawing (for these small projects): Allowable bearing capacity min. 1500 psf to be confirmed by a geotechnical engineer. There's a few geotechnical engineers here that do a visual inspection in an open trench during construction for a low cost.
@MIStructE Why don't you use a simple multiple ply LVL beam? I personally don't trust a residential contractor to use the correct size of screws and spacing.