I think the easiest thing to do in that situation is put a mattress on the floor. It dosn't have to be your family bed up on its frame (although that might improve consistency) but any mattress on the floor in a decently childproofed area. For a while when we were trying to sell our house, we had to put our bed back up on our frame to make it look like "every man's house". Our second child was about 6 or 7 months so we put a futon next to my side of the bed so I could nurse him to sleep for his naps. When we had a showing, we would push it under the bigger bed.

You could even try moving a crib mattress on the floor and nursing her down there. Its not quite as long for an adults legs, but it works! I have done that too!

Hope this helps!