racial trait +20% and evasive armors

[geoschmo]

You've already hit on the only real course open to you at this point. Massively outproduce him, and be prepared to lose a lot of ship. And make absolutly sure all your ships are trained before commiting them to battle. Otherwise you are going to see some utterly horrendous battle results, like losing entire fleets and only slightly damaging a handful of his ships even when you have him outnumbered 2 or 3 to 1.

Some people more helpful then me may come up with some things to try, but honestly they aren't likely to be very effective.

My only suggestion is to take combat modifiers next time.