The Mysterious Chinese Woman has been vindicated. Debbi from the Banana Cantina here in Puerto Vallarta sent me an email explaining this sculpture:
It is a Mexican woman washing her clothes in the river. I guess that explains why it is located right by the river. I will have to say, in my defense, that I have seen many a Mexican woman washing their clothes in the river and none of them looked anything like this sculpture.
On the other hand, I have never seen a Chinese laundry in Puerto Vallarta either.