That's a first for me!
Is the home you rent situated on many acres, or is this tent within a few feet of the house or in the backyard?
My initial response would be to say, no, she can't invade your privacy by erecting a tent close by - I assume you rented the home AND the land it is on. read your lease!
Is this a temporary situation, or is she planning on staying there indefinitely?
You might want to check with an attorney if you can't straighten this out with her.