If there's a need for a tag then how about something like "space sos outfit" or something along those lines. Mind you, something less cumbersome than that would be nicer, but that's honestly all I could think of at the moment.
Well, in the Haruhi Theatre near the end of when when the costumes debut Haruhi mentions something about a Galactic Patrol. So how about something like SOS_Galactic_Patrol? It's not the best, but at least it's more lively than my previous suggestion.