Well, to clarify.. for a Waypoint action (CAP, ORBIT, SEAD etc..) they will perform THAT action until flagged.
You can put them in a holding pattern (ORBIT) until FLAGGED, with the NEXT WP having some action (CAP, SEAD, etc..) so they will be more or less inactive until leaving orbit.
No advantage to using a moving vehicle it won't help you do what you wanted to do..I was just pointing out that although aircraft can't start INVISIBLE, moving vehicles CAN..for whatever use you may want to make of this in the future.
One thing I could think of is to lay SAM/FLAK traps. Since, in the SIM, you can't have the SAM/AAA operators selectively shut down their radars, you could have an AREA or MOVING AREA event turn on SAM/AAA vehicles (2S6, ZSU, SA-8 etc..) when the player flies over, as if the SAM operators were hiding and waiting for the right moment to engage.