I'm not exactly sure what to call the accent I imagine the waitress having (I think I'm imagining something pretty specific), but any accent you can imagine "sweetie" sounding natural in works, really.
I don't like going overboard with the "fourth wall" jokes, even in a non-canon story. Twenty comics into a story like this in which people are undoubtedly expecting gratuitous transformations, however, I feel there should be some even if the transformation game itself hasn't started yet. I felt one more nod to this being non-canon would give me a lot of leeway to have Rhoda just do whatever while in this restaurant.
Nonetheless, I found I wasn't satisfied with Rhoda's "I'm obligated to abuse my power" excuse, which is why the waitress says something. I like the extras being on board with this nonsense.