WARNING! This can erase your saved game!

Go to Design Maps,then make a new map. Fill the whole top row with Tanks, then the 2nd row with MD.Tanks, then again with B.Copters until you can't go anymore. Then, make some of the Tanks and MD.Tanks Bombers (All Orange Star). Save the map without a name and go to the Field Training mission Naval Combat. Do everything what Nell says until day 2. When you can do what you want, unload your Cruiser, then end the turn. Your T.Copter will get destroyed. Go back to Design Maps. Pick the last map you made (The weird one). Then, pick the delete icon, go to the top-left, and HOLD the button while deleting everything on the first row. Go back to the left with it (Keep holding it!), then do the same with left row. Continue this until Nell comes up with a message that the Orange Star Army has lost! Now Design Maps will act like a normal Mission, but you can still place units AND attack! Press certain buttons to do certain things, but pressing one button (I think B) will freeze the game. Another button will SOMETIMES delete your saved game, so do it at your own risk! I tried it twice, and luckily, the game isn't screwed now...

I heard that you can also edit campaign maps, but when you edit them, they will be that way in the Campaign, so watch out!