Take a spare/spinnaker halyard and wrap it around the rolled headsail to prevent an unexpected storm from unfurling the sail (with potentially dramatic results), and/or tie the clew tightly with sail ties around the roll..
Is your winter cover supported?... if not and it's a tarp over the boom/sail cover then you're likely to get some chafe on the sailcover from the tarp.. Since the main is already down and it can't fill like the headsail I'd be tempted to take it off. But... you're hauled for the winter so you're likely in an area where humidity is not going to be high so maybe you'll be OK as long as your don't trash your sailcover...
".. there is much you could do at sea with common sense.. and very little you could do without it.."
Capt G E Ericson (from "The Cruel Sea" by Nicholas Monsarrat)
1984 Fast/Nicholson 345 "FastForward"