That's exactly the same problem which I had, especially at night with the overhead. Varifocals didn't work satisfactorily for me in such a confined space as a cockpit with so many rapid changes of vision depth necessary.
A good pair of trifocals, at considerable cost, with my old bifocals as back up in the flight bag, worked well. I had the lenses coated for extra protection and took very careful care of them, wearing one of those granny strings around the neck lest one hurl them around the cockpit in moments of fury at the activities of crewing.