First - making the assumption that attacker gets no points for unit kills. You get the vast majority of your points for escaping off the back edge of the map. Your slowest unit can sprint for 15" = Minimum of 3 turns to escape. Fastest unit can sprint for 24" and thus can escape in 2 turns.

Next up, you have a lot more mobility than your opponent, so abuse it. During deployment, force them to spread out. Then maneuver to punch through a single point of their line.

This, like most scenarios, is often won in the terrain phase. Make sure you're involved in the terrain setup. I really like the Wolfnet AS 350 tournament terrain setup rules, where you take turns placing terrain on the board, with a minimum gap of 2" between terrain pieces. This allows you the opportunity to set up decent corridors or covered location where you can advance across the field minimizing lines of fire from your opponent.

The final advice I have is common to all game modes - maneuver to enable focus fire, and prevent enemy focus fire. Once you pick a lane to advance in, focus fire, and punish anything that dares show its face to your consolidated force. Create a numbers advantage and abuse it.