I think part of the answer to that question is how healthy the coral is, and how it has been taken care of. I've never kept anything in a bag that long, but when I visit my in-laws in KC I'll stay maybe 3 days with a coral in a bucket w/an air pump like you described and a heater, along w/maybe a gal or so of 'fresh' water w/no major problems. Just be sure to keep the temp stable. I think that's the biggest issue since the bag isn't insulated and the temp can flux so random. I think most die to heat/cool issues before they do actual water quality when they are in a bag, unless it's not healthy to begin with.
