Actually, I think most English teachers have finally abandoned that silly rule. Jill's writing is undeniably weak, but it in my opinion it would only be worsened by awkwardly shifting the entire prepositional phrase to the end of the sentence. ("The church at which we parked" is weirdly formal for the context.)
One good rule of thumb that's worth holding onto, however, is to omit a preposition at the end that isn't part of a prepositional phrase. For example, it's just "Where are you?", not "Where are you at?"