Vortex
I think you're missing the point that lots of people have already made.
You could put more than 7 GR9's in theater but you wouldn't get any more air support.
Why?
Because there aren't enough pilots to fly them or engineers to keep them flying, or at least not without increasing the length of individual detachments wich would soon mean you wouldn't have any pilots or engineers at all.
So why don't we get more pilots and engineers?
Because the Government have decreed the size of the air force (too small)
and they have to balance their manpower between all fleets.
If the government is willing to increase the size of the air force I'm sure we'd be willing to provide more air support, but until they do we do the best we can with the forces we have same as the Army and Navy are doing.