Hope you're back on top form by now SW. It sounds like the Wilmslow outing was good preparation. I'm always banging on about the
Marathon Talk podcast; episode 64 included a nice discussion on tapers (35 mins in) - too late for us to change anything now but it's actually a nice confidence booster to listen to.
I can't collapse the costume unfortunately (in fact please don't mention the word "collapse" in the context of a marathon!), it has two garden canes inside it for stability. I will just have to go with the flow and hope for a following wind. Would be good to meet up in Preston Park for a team photo if poss, although I'm not putting the costume on till the last minute - i.e. until toilet breaks are definitely complete!