Probably the answer you do not want to hear...
If there is a substantial difference in shoe sizes, maybe the best solution is to buy two pairs of shoes with proper sizing for each foot.
Wearing different size socks does not sound like an optimal solution, if there is that much of a variation in shoe sizes. In hot weather, I would not want to wear an extra think sock. and visa versa for cold weather.
I am fortunate, to have the same size feet. Salomons are perfect fitting shoes for me. I can wear different thickness of socks for varying conditions, and lacing up the shoe provides a perfect fit. I have never gotten a blister with either of my Solomons.