What do you do in GAC when you have a high GP disadvantage?

You haven't provided us with any useful information to help you with your strategy.

Have you looked at your opponent's GAC history to understand why they are being matched with lesser GP opponents? Chances are, there are clues there that will drive your strategy. My baby account at 1.4m was paired with a 4.5m opponent. But when I looked at his history, he auto-sets and never attacks. So I can do one token attack for 10 banners to win the round. You may have a similar case.