Your guys are more easy going than I would be about that 230.70 "inside nearest the point of entrance of the service conductors" language. I would be OK with the 18" if that was the best you could do but 15 feet after you have already hit a cabinet inside would be a no-go with me. I would have you making that first box a service disconnect for the full monte and the run to the next box would be a 4 wire feeder.
230.6 defines "outside of the building " as
"(2) Where installed within a building or other structure in a raceway that is encased in concrete or brick not less than 50 mm (2 in.) thick"
Unprotected conductors inside a building are the kind of thing that keeps me awake at night, even if it is not my building.
