I've let someone use my abbotdavis boot (had it on for a long time...months (not poulticed for that period) but had to used he boot to keep it clean and dry etc and it still came back in once piece, did it fit correctly? only reason I ask if mine was a little too big for this other ladies horse, yet it still kept in tact, so it might be worth trying a different one?
baby's nappy on top of the chosen poultice, one of those sticky bandages, and i wrapped mine in a good quality plastic bag (the M&S bags used to be great!) lots more gaffa tape around the toe again, tended to stay on (most of the time!)
Highly recommend using a nappy, they fit perfectly and the tapes seem to be in just the right place. I then use parcel tape and he can be turned out all day with it staying in place.