Not so much full as just round and soft.
Then is sounds like it's not emptying completely overnight. It won't hurt to try a crop bra if it's stretched out. She's fairly young, but some can overeat and it gets stretched fairly quickly.
The crop function will still need to be monitored even with a crop bra. She may benefit from daily massages to get things moving. I'm sure you have a source of poultry grit available, while it won't cure or eliminate pendulous crop, it is helpful for digestion and gizzard function.
@azygous is excellent in walking people through crop issues, so hopefully she will chime in with her thoughts. Some people do make their own crop bra, but they can be purchased as well http://www.hensaver.com/Crop-Bra.html