Go with the bunkhouse. Let her take ownership of her own space.
I usually go to sleep much later than my wife or kids. It's nice to have the center of the TT - couch and dinette - to myself to read or just relax.
PS - we started very young with our kids - no sleeping in our bed whether we were traveling or not. If the kids were really scared - nightmare, lightning/thunder, whatever - they slept on our floor, never our bed. You have to break that habit; sooner rather than later. Otherwise, before you know it, you'll have an eight year-old that still wants to sleep with you.
