A different result to destroying the HQ could be to:
1) Halt all strategic object repair time regardless of the health of the corresponding strat factory. For example, when the HQ is down, the downtime for AAA guns will be full even though the AAA base may be at 73%. Normal downtime as a function of the AAA factory health will resume once the HQ is repaired. The downside is this would create a strategic bottle neck affecting all strategic factories and thus all fields; the upside is that it only lasts as long as the HQ is disabled and players will not be encumbered to blindly find a fight.
-or-
2) All radar forms are disabled for players in flight, but still function for players in the tower (as long as radar towers are not destroyed). This setting is possible, but I don't know if it can be linked to the HQ health and changed while the arena is in play.