40 is pretty cold for even lager strains of yeast. I would insulate the fermenter as well as possible inside the chest freezer to maintain the beer temps more consistently. Wrap in sleeping bag or something similar.
Bigger question is: if you have a temp regulator on your chest freezer, why not bring it inside? Or at least garage where it might be warmer? Would make a perfect lager.
Primary #1: Empty #2: Empty
Secondary #1: Belgian Golden Strong #2: Dark Belgian Strong #3: Empty #4: Framboise Lambic
Kegged: RedHook ESB clone, Fat Tire Amber
Bottles: Surly Furious clone, Kicked by a Moose Scotch Ale, Apfelwein, Russian Imperial Stout, Trappist Dubbel, Carmelite Tripel
On Deck: Kölsch IV, Altbier II