Back in the 70s I was using a BSA Lightning as everyday, year-round transport. A solution to cold hands in winter came in the form of an Avon handlebar fairing, as used on those 50s police BSAs. The type that pushes the headlamp forward and, to be frank, is not the most attractive 'extra'. Despite the poor aesthetics the impact on keeping the hands warm was pretty good, simply by keeping them out of the breeze. Oh, and it didn't load the electrics either, of course!