I think that Double Easy (double-eee-zee) is quite clever, and would encourage its adoption. Even for those of us that might naturally say zed rather than zee, we would get it.
And while double-eee-zed doesn't pick up the extra meaning, it isn't any harder to say than eee-eee-zee which is what I've tend to know it as. OK, one extra syllable but it still flows.
PS. I've said eye-two-cee for a few decades rather than eye-squared-cee, but while I am certain to not be the only one, I am also not sure how prevalent that is.