I would say that adding more steps for Foxy to go through before she charges would probably be the best option. As it stands, there are only three steps before she charges, but increasing that to five might slow her down enough to be manageable.
Like, step 1 is the curtain drawn, step 2 would be her peeking out as she does, 3 could be her stepping off the stage, 4 could be a stretch or something, and 5 could be her in position about to bolt, as it is in the game now.