Strike - Air Intercept Missions (alt - speed)

[Knightpawn]

In air intercepts that either open-ended (no targets just minimum radius) or with assigned targets only (no flightpath) how can one give instructions about altitude and speed during the mission design face?

Assigned ACs after take off, tend to climb and operate at 36000ft automatically, which in certain cases is suicidal because of presence of S-300 or S-400; or targets could be helicopters in where it may be better to attack form mid to low altitudes.