Have a new launch site set in the air for air-launched vehicles, like spaceship 1, the X-15, and the MAKS space plane. It can be set with adjustable altitude, direction, initial speed, and coordinates. It can also have a relatively small size limit, mass restrictions, and higher cost(for career mode) to make it fair.
I built a sailplane and then realized it would require an engine to fly. So, yes, this is the thing I wanted.