You'll want to add sorbate if you're going to back sweeten with any form of sugar so as not to cause refermentation in the bottles. since sorbate and MLB don't get along well together with a resulting geraniol odor, you will need to also add lysozyme to kill the MLB before adding sorbate...
In Montana fall can come early - so that means chilly nights. I used my garage for fermentation area. to keep things warm, i made an incubator with 2" foam insulation boards. i just cut them up and put them together with duct tape including a hinged front panel so i could roll fermenters in...