Dragons are pretty hardy, I know it goes against this boards general recommendations, but your dragon will be fine in 50 degree temps for the night. I wouldn't ever recommend keeping a dragon in temps like that at night on a constant basis, but in this case, I feel its appropriate to mention its not THAT big of a deal.
EDIT: Removed some things after re-reading some more of the thread.
-Brandon
EDIT: Removed some things after re-reading some more of the thread.
-Brandon