Thanks all.
I do have a baby blanket that is hers for her to sleep with on the bed. I think she has accepted that she won't be allowed way down there, but it's okay if she does it at the very top. Although I wouldn't mind it if that's what she wants, it would just worry me way too much to let her stay under there. I would never get any sleep worrying about what I might find in the morning.
So we have resolved it and she seems to be okay with it. I just snuggle her next to me and if she wants to venture just a little ways in, that's okay.