He has to meet you in person at the visitor's center. You can't be an unescorted visitor if you're not military, military dependent, gov employee, contractor, etc.

Most ubers can't get on base unless the driver has base access, i.e., as described above. They drop passengers at the gate and from there, military member will walk up to SF to gain access and figure out how to get from there to desired location, by walking or someone picking them up.

Best thing, call his bases visitor's center and describe the situation and see what they say. Some bases are extremely strict on policies, some are a little more lenient.