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:Spruced Winter Warmer #2: Empty
Secondary #1:Berry Rhubarb Wine #2: Empty
Kegged: Cascadian Dark Ale
Bottles: Surly Bender clone, Big 50 Barleywine, Framboise Lambic, Dark Belgian Strong, Kicked by a Moose Scotch Ale, Russian Imperial Stout, Sparkling Elderflower Wine, Barolo Wine, On Deck: Orange Pale Ale, 2H IPA