Oh, I think I get what you're saying. If you wear say a man's XXL pair of gloves, finding bigger mittens might be hard. (I have small hands so I didn't get what you were saying, and I have to admit, I never even thought of that problem.)
What about a stretchy pair of mittens? Ok, this might not be really pretty like you bought it from Nordstroms, but what about making your own pair of fleece mittens? Think fleece material, thread, and elastic. Oh and a needle. You could make a pattern big enough to fit the gloves. Cut (ok, I forgot to add the scissors,) and sew. I would make the wrist part with a casing so you could use elastic. I would think that would also give you a larger margin of error.
Also, making the mittens should be easier than the gloves.