With ISO 100 film It's really going to need to be 5.6 at the smallest in my experience. I've never seen starlight cause a flare in my Canon and Mamiya glass. Would this be a problem in a LF lens?
What I have seen is perhaps not so much flare, but the ability to render the stars as the smallest point possible. At both extremes of f/stop, the stars might just look a little larger, and star-trails a little wider. Might be perfectly acceptable for what you want.
At least with LF landscape, a bad day of photography can still be a good day of exercise.