I've only tried it twice, almost beat it the first time (I think the pirates had everything deployed or destroyed), but the second time I got my butt handed to me. I was doing it with battle size 400. I haven't really done any sort of balancing on it, to be honest.
My strategy was to deploy cruisers, Enforcers, mining pods, and some Tarsi first, then deploy all the Buffalo (make sure you have enough DP to do so). I put down two defend points, one close to the middle of the map and one towards the rear. The Buffalo were assigned to the rear point and the rest to the front, then I just stayed near the front in the Eagle and tried to grind down the pirates.
Keep your shields down except when blocking missiles/asteroids and don't be afraid to take a quick vent, because you
have to keep firing.
I was trying it with only 3 command points, so maybe ordering the Ventures to escort you with the defend points for everyone else would work better.
The Lashers have more firepower than the Tarsi, but they're more likely to overextend and die.
Warthogs are scary when you haven't got all of the pirate's (2) carriers.
Like I said, I haven't tried it much. I'll probably try again over the weekend once or twice. Any specific feedback on how unbalanced it is would be great.
Edit: For giggles I turned battle size up to 800 and played it. There were only 21 out of ~68 pirate ships left when I died. So bitterly-contested defeat for me. There were so many wrecks... I think a wreck hitting my engines is what killed me.