It was a single prototype. One of my minor claims to fame in life is that I worked with a guy who was a test pilot, and actually flew in this aircraft.

Of course, your larger point stands however, and general there's no "type conversion" craft like you see in other two-seaters for this purpose. That said, if you had a solid flight background in other types of aircraft, it'd be unlikely that you'd have issues in the A-10. It's reportedly an easy craft to fly, there's little peculiarities that would give a pilot issues like you see in some high-performance craft. Straight wing, low landing speed, no built-in aerodynamic instabilities or anything like that.