I worked in a "smaller" hospital...and I understand your situation. When the peds census was low, they would float us to adult floors. When the peds census was high, they would float adult med-surg nurses to our floor. I came from adult med-surg, so it was not a problem for me. However, for those who had never done adults, it was incredibly difficult (and dangerous). Adults have issues and problems that peds pt's don't.
After I had left this facility, I heard that a pt on peds had died (a gastro pt) that was being taken care of by a floating adult nurse.