I'm with IAN-UK . It was fun to see if it could be done.
Yes I could get a routing at ~$3k. It would have been nice to be able to brag about doing it BUT the reality of that trip was too risky (no padding), too many Y night flights and not a great deal of fun along the way. I think I would be doing it if I could have broken the flights into two or three chunks but I haven't got the time.
Good luck for all those who do try.

Final PS - I have no idea how usable the airmiles would be, that was a further risk for me