Generally speaking many lowland plants can tolerate colder than prefered night temperatures IF the day temperatures are nice and warm.. 85 is good. But it needs to be consistantly that temperature. Some plants in my experience will dislike the cold nights regardless of the day temperature. N. bicalcarata is one of them. Too cold at night and it will turn black and it doesn't matter how warm it was that day. 55 is way too cold for this one imo.
Some you could try.
N. ampullaria (red forms seem to deal better with the cold)
N. viking or globosa or mirabilis globosa.. or whatever you want to call it
N. rafflesiana - probably be ok but may not thrive like it should
probably some others that I can't think of off the top of my head..