Hi Chris,
Unfortunately, we do have cold spells in winter that's too cold for even highlanders. You are about two hundred miles north of us and inland, so temps can be more extreme. Because we grow commercially, we maintain a very high standard for the plant quality. I'm sure they would tolerate rougher conditions, but the plants would not look so good. I heat the greenhouse when temps are predicted to drop below 50 F. Night time low temp is always maintained at 50 or above. Days are purposely kept hot and humid, to counter the cold night. This is key to growing ampullaria and bicals. They will tolerate low night temps, as long as they have hot humid days following. Our bicals were subjected to one night with a low down to 48 F when we had a heater flame-out. There was absolutely no damage, but the following day was sunny, so in the greenhouse it was 90 F with 80 percent humidity. When you step in the greenhouse at times like this, eyeglasses and camera lenses fog over.
We find albomarginata enjoys coolish nights, and really can grow quickly if given bright, very humid conditions. Also, a very well drained mix and somewhat dry at the roots. We grow albos in clay pots so they dry out faster than Neps grown in plastic.
It's gonna take trial and error to see what works in YOUR conditions. Sometimes a minor tweak of one variable can be the difference between a plant struggling to live and growing like a weed.
We have customers in Palm Beach who grow ventrata outside year round. One lady said her ventrata got so big it started vining up the nearby trees and had to be cut back. It was then she found huge pitchers in the undergrowth, and one had a partially digested mouse in it.