Problem more or less solved in OCs vs Corsairs, when BOTH faction were making capital raids, just change in proportion: time to reach distance/ fun from raid. Ration probably more than 1.
Limiting players with caps.... not sure. This could be a bit unfair to those players who worked hard to get capital ship, and then, they realized, that its just big flying scrap, and you cant do much with it.
You can limit capital ship usage to minial, by decreasing actions, where capital could be use. In simple word saying, make cap play boring. But this should be... mentioned somewhere, for new players. That playing on capital gives you less funn and less opportunities to take part in actions.
Like cap ships only for special events and only for Offical factions.
Then imagen players amount on server.
However, before there no player bases awailable-battleships are key for trade. People will trade, mine for those caps. Trade wont be so popualr and active without caps usage. No trade, no pirates. No trade, less RP and fun. This goes for caps.
Last thing to say, mod was developed to use capital ships there. Trying to change it will brobably kill mod.
Situation called capspamn- its just showing, that things went out of control.