That's a brilliant idea!!! Mine are all driving me mad at the moment. I'd have to wait till their summer coats came through before the deed was done though - it can't be much fun brushing a clipped one?
I have to confess to a lack of expertise in the actual taxidermy itself, but I can share my experiences with you.
It would cost £800 plus for a 16 hh horse to be stuffed (I phoned when drunk once), however, apparently the taxidermists do prefer if the horse in question is dead before they start
Alternately, my local Chinese restaurant, back home in Scotland offered me a 'You bring your horse in: we'll cook it for you' deal that I toyed with for a while.
Hope this helps.
S