I just am about 2 weeks away from my level 5 GC so take this with a grain of salt...I could be wrong. But here is what the book says:
"An entity licensed on section 40-11-410(1),(2),(3) may act as the sole prime general contractor on a project if 40% or more of the total cost of construction falls under one or more of the licensee's license or subclassifications. A properly licensed mechanical contracting entity must have 51% of its licensee subclassifications in a construction project to be listed as the sole prime contractor."
In reviewing the statue directly he might be able to go with a "General Contractor-Highway" and then go back to a "General Contractor-Building" to complete the build. Or you could probably go with a "General Contractor-Building" and, depending on the dollar value of the site work relative to the build (less then 40% of the project), they would be able to perform the site work as part of their license, or direct a "Mechanical Contractor" with a Grading and Paving license (eg. some guys with trucks and dozers) to perform the work and they would be able sign off on the adequacy of the build.
Also, as an FYI, he will need to verify that you're under an acre otherwise you will need an environmental study to move that much dirt around.
I hope this helps. From the sounds of things it may be easier to hire a Category 4 or Category 5 contractor and just have them GSD rather then trying to manage a bunch of specialty contractors.
-Jeffrey