I don't know. It should be keys which aren't used for standard things.
Last night I used the base land auto pilot and watched from the tower at BB. Very cool. I'd never come in that fast manually. I like the Shuttle-A more now that it can handle people and cargo.
A suggestion. Could you put the starter on s instead of k? Since other add-on ships use k for doors or the docking nose cone, someone might hit k at too low an altitude and not be able to recover when the engine dies. Unless this thing can auto-rotate that is.