I have both normal and sunglasses in the same perscription. As I am old, I need reading help too. I went for bifocals (not varifocals) because as a Heli pilot I need the outside bottom quarter to be distance, and I can get that with bifocals. Also, no risk of losing something in the gradient of varifocals.
Mostly I wear the sunglases and a peaked cap - strobe effect through the rotars can give you a headache.