Peña Escrita, is that you!? Gamoniteiru, hello?
In fairness, the hunt for new Spanish mountains is kind of my thing, the amount of bits and pieces I've done on the subject on these boards is pretty OTT, what with four (4) Race Design Thread Vueltas (no repeated summit finishes) and the 21 ESP climbs the Vuelta should use thread (+ a number of honorable mentions). And I'm far from done with the possibilities of Spain too, since much has yet to be said.
There was a rumour a couple of months ago about the Parque Eólico de Lubián, which hosted a summit finish in the Vuelta a Castilla y León this year. It's only about 7km long, but would fit the Unipublic modus operandi perfectly:
It can't be attached to any difficult climbs very closely (Peñón would be about 50km out), and has those steep first 4 kilometres. However, I think they may also have been talking about for a future Vuelta with the mooted Porto depart.
In seriousness though, Coll de Pal or La Cubilla ftw.