Welcome to NGA
@Frobby -- I'm happy to see another Yooper here!
What perennials do you have growing in the trough? A lot of things are surprisingly hardy, I have some sedums (Autumn Joy) and some chives that I've stuck into pots and left them outside over the winter - for multiple years - and they have survived without a problem.
I think I would be inclined to put a "low tunnel" arrangement over the trough to give it some protection, but you'll need to keep the issue of snow load in mind. Maybe just a simple A-frame over the trough, covered with clear plastic.
