I know what you mean. I wear multi-focal glasses. On my LR bolt gun which has a Burris XTR II 5-25 depending on how I hold my head I'm looking through a different prescription and the image is blurry or the eye box closes. I know consistency is the key (exact same position, grip, trigger pull etc) but trying to get my head in the exact same spot with the glasses to see clearly was too frustrating.
My solution? I bought some reader safety glasses. I look through the un-magnified top while shooting and have focused the diopter to my uncorrected vision so it's clear and crisp. But I can sit up and use the reader portion to look at DOPE book, Kestrel, and anything I need to see up close.
Home Depot (and lowes, maybe) sell them in multiple strengths in clear. You can find them in smoke or other colors with some quick google-fu.
Hope this helps.