Just a suggestion for the Holding Action mission...
Turn the Defense Platform back into a Listening Post, and make it ALLIED with the Attacker.
The Attackers objective, scan the LP and escape (either by destroying the Defender or by withdrawing) In this case its exactly the same as the Stock Holding Action.
The Defenders, however, do not know where the Listening Post is, its away from them. Their objectives, find and destroy the listening post before the attacker ships can scan it...or, destroy both the listening post and the attacker's ships. Give the Defender 125% bpv of the attacker, should the Defender's BPV be less than the threshold, give him the option to "Call for reinforcements" from the Communications panel. After the button is selected a suitable ship will spawn near his starting location, in a random amount of minutes, using the countdown timer in the corner that, as far as I know, hasn't been used since SFC1's competancy tests in the academy.
Doable?