Ships: if I were the attackers, I'd bring 4 bombers, instapwn any transports, then leave. Easy win, no fun except for the blue message freaks. So to avoid this kind of outcome, I would suggest a limit of 1 bomber for every three fighters, on both sides. Of course, you can still target just the freighter with only fighters, then leave without shooting any of the escort fighters. To avoid that, I suggest taking inspiration from singleplayer, and having the Dragons use a transport to board the Samura ship. So now both sides have something to defend. Major victory for the Dragons would be capturing the Samura freighter, major victory for Samura would be getting to Sapporo intact. Minor victory for the Dragons would be blowing up the Samura transport, while minor victory for Samura would be blowing up the Blood Dragon transport while not making it to Sapporo. And both sides lose if both transports are destroyed.
Also, no gunboats. Maybe when the event moves to a more critical area for either side, but initially, no gunboats.