Hahahahaha. What a nightmare. Worst case scenario. But I have good news for you....
I had the same thing happen to me on a brand new, freshly powder coated, expensive, magnesium, racing motorcycle wheel. I broke a brake rotor (defective
) bolt off. Drilled it, inserted the easy-out, turned, and SNAP. The was no other access than the front side, where I already tried. It would be a HUGE LO$$.
I called around and asked around among the racing folks, looking for suggestions for a remedy. Someone told me, "Just have it lasered out." I said, "What???". Unbeknownst to me, there is an industry for exactly that. Mostly for automotive engine applications, but a bolt is a bolt, and an easy-out is an easy-out. I found a place close to me and they lasered it out for $35.00. They let me watch. I gotta say, the precision of the machinery, jig, and process were fascinating. When finished, the cleaned up threads looked better than the factory threads.