[Nodachi]

Here's a thought;
Turn 1: change all your ships over to "Don't get hurt", move into (not attack)the same sector as the HW, assuming he doesn't have any ships there your ships will flee to the edges of the map and never get touched by the weapon platforms. You now have blockaded his HW and IIRC that really hurts in Proportions.
Turn 2+: chage all your ships back to "Capture Planet", wait until he attacks you, the combat should start with you right on top of the planet and getting the first shot.
I'm not entirely sure this'll work but it might be worth a try.