If you damaged the threads that badly, I suspect you may not have the finesse for some of those ideas. The dropout saver seems like the best idea, with a helicoil insert also an option.
Originally Posted by
Al1943
You just need to "Chase" the threads with a tap matching the original threads.
Rather than use a tap and possibly remove more material, try screwing in a rear axle from the back where the good threads are, and see if that chases them to any advantage.