[zallus-k]

Instead of Peacekeepers, just make a 'Central Government' tag, for anyone wanting to help out. They'd still live/work in their own kingdom, but they would live on the ships, travelling between different kingdoms to help out. Yes, the same general idea, but it just sounds too much like the peackeepers were thrown over the fourth wall, unless they're just normal people, who happen to work for a government agency.

And as for uniforms, you mean like creating a 'Graalian Military' or something? It sounds more your idea. The way you have it, you could just as well call them GPs. Unless the players can just sign up during the game, it dosen't make sense.