[officialtony]

Having seen how crowded an infield gets with the ladies jamming in on bunt attempts and stolen bases and people running everywhere, I can't imagine doing anything from behind the pitchers plate. I rarely feel safe outside the perimeter as a Base Umpire. I feel like I would be in the way and impeding the abilities of the infielders.
What I would do . . .
is back up from the plate, stand up and make sure I did not get beaned or hit by any of those wild pitches and call everything a ball I wasn't sure about. When the coach complains ( and we all know he will ), explain that for your safety, since the pitcher has lost her control, you will be calling the game this way while she is on the pitchers plate. If he doesn't get the message, at least you will not get beat up anymore and he will probably lose the game, which will not make the pitchers teammates or parents very happy.
Certainly not according to the book, but your options are quite limited.
My humble opinion.