B.C.
I'd agree to let her sleep on her front. If you're not smoking in the house and you don't have stuff in the crib (blankets, bumpers, toys), her risk of SIDS is pretty low.
My son prefers to sleep on his back, and started sleeping through so early that we ended up putting him in a orthotic helmet for the flat patch at the back of his head! The helmet hasn't been very problematic, but if we have another child I will definitely consider sleeping him/her on the tummy.