In reply to theomoore:
"Tell her to stand much further out from the wall."
Please Don't do this. unless you have. No, just don't. Please.
"At the wall we can attach a weighted bag to her. However I don't fancy carrying a really heavy bag on a walk in. Do you have any suggestions?"
Have you tried leaving the weights at home, then filling the bag with rocks at the crag?
You don't have to take the rocks home with you, no one will mind if you leave them at the crag.