Last one...thank heavens, that took forever.
Mistakes, only one. The split extended a long way down the butt and I'd fully intended to bring a ratchet/strap to keep it in place while I mad the cuts. Anyway, I forgot it but compensateted to an extent by tying it up with a rope and cutting away very carefully in anticipation of any changes in compression etc.
Also, I did rush the top on the first day because I was worried about the winds that had been forecast, they never came.