It would probably be fine. They like room to swim, but they don't have to have it. Matt was keeping them in a 24 gal. (and by them, I think he had three or four). I wouldn't keep more than a pair, though, since I've seen them get pretty aggressive with each other.
"Reef safe" is a relative term. I've seen lots of yellow tangs picking at clams and LPS. Are those "reef safe"? Given that these are already eating mysis shrimp, as long as you keep them well-fed they probably won't do much damage.
Thanks, Gale. I think I'm going to wait for the heat to abate a bit before I get a new pair, though.