The problem with wild caught snake is that not all of them will eat for you.
I took in wild caught snakes in the past and had mix success when it comes to feeding, of course granted those animals were injured and this probably played a huge part.
As mentioned high 80 low 90 is overkilled to me.
What I would do is get a very small tub about 6 quarts, and have some aspen in it, sometimes kings just like BP can easily be stressed and offering a tighter enclosure can help.
No it won't that is YOUR human emotions doing the talking, Kings among other snakes brumate and do fine in their natural environment during the winter and do not require any help to survive the harsh winter conditions (which we know in the south are not that harsh).if I let him go he will most likely die from cold weather.