I'm not an expert on food safety, but I found this on the USDA site "Bacteria grow rapidly between the temperatures of 40° F and 140° F. After food is safely cooked, hot food must be kept hot at 140° F or warmer to prevent bacterial growth. Within 2 hours of cooking food or after it is removed from an appliance keeping it warm, leftovers must be refrigerated. Throw away all perishable foods that have been left in room temperature for more than 2 hours (1 hour if the temperature is over 90° F, such as at an outdoor picnic during summer). " I've had food poisoning before, and I would recommend erring on the cautious side.
I've been smoking on a BGE for over 8 years and I've never had one go out during the night. I have had the temp lower sometimes on a winter night and increase on a windy night. When doing an overnight smoke, I first fill the egg with charcoal (lump and not briquettes) and once I have achieved the desired temperature I make sure to check on it after an hour to make sure everything is fine. Good luck.