I agree with Noe about the confusing use of "hidromiel" or "aguamiel" in Spanish speaking countries without a mead making/consuming tradition (every single person I have ever had try my mead, with the exception of akuek, had never tried it or, in most cases, even heard such a thing existed).
The fact remains, however, that here in Chile and in other wine-producing countries, the word "Vino" can legally be used only for labelling fermented grape wine.
However, I personally think that rather than trying to promote a new word like Vinomiel (although I like it), I think it might be better in practice to push for the adoption of the word "Mead" in Spanish too, in the same way that "taxi" or "hotel" are used. Those are foreign words that did not have a local counterpart. Hidromiel, while it may exist in dictionaries, is virtually unknown and sometimes confusing, for the reasons Noe described.
Using the word "mead" would also make the international efforts promoting mead useful in Spanish-speaking countries, as well as opening up markets in other countries if a mead market actually develops internationally.
Just my two cents
Bonum vinum (mead) laetificat cor hominis - Good wine gladdens a person's heart