Okay so here's an idea just to throw one out. Probably done before and if it has then okay then.
Setting is planet with floating continents and islands. Why? who cares.
build communities, gather rez, forge empire, battle other players and sky tribe monsters
Battles can be 3 ships by one player or 2 ships a piece of up to 4 players.
Ship frames customization by space not weight. Not restricted by 'number of slots'
I like rocking the boat in my own little way. Keeps everyone either on their toes or on the rear.