OK, but why an outsider. Why not make a 3rd string defenseman from your own team put on the pads and play goalie?
My guess would be that even a minor league goalie would make a better goalie than someone who doesn't play the position.
Plus if the visiting team needed the emergency goalie, it would be a bit of a conflict of interest for a 3rd string defenseman from the other team to be their goalie.