Hi i really like the GSB and how it look, and how it is played.
As this game is really great it could also use different type of mission, than just elimination and survival.
My suggestion is to create Convoy escort mission, where should be difference between attacker and defender, Defender should construct special type ship “Transport”, in size similar to cruiser, with only support systems and relatively high weight, so it would be slow in any case.
Defender then place transports, and assign them ships for protection.
Transport would have order to get to opposite side of the battlefield.
Attacker would set up his ships on top and bottom of the screen, and its ships would have acces to a new order “attack transports”.
Victory would be calculated based on how many ships get to the safety or was destroyed.