I'm glad that I learned about Ramón Sostres from this thread. We owe a lot to those pioneers with their "build it and they will come" vision for the Camino.
I think, though, that El Ramon, as portrayed in the film, owes less to Ramón Sostres than it does to Alfred Hitchcock's Psycho. When "El Ramon" goes upstairs to serve himself wine and conduct both sides of a conversation, he is like Norman voicing the dialogue of a son and mother. It's said that Hitchcock chose the name Norman because it sounds like "Normal" and the name Marion was chosen as an "almost mirror" of Norman. Perhaps Estevez had all of that in mind when he planned this scene - and the fact that his father's name is Ramon may have convinced him that it was a good idea. Unfortunately, I don't think that he really establishes a reason for the pilgrims to be scared. You feel Jack's discomfort at the lack of an inside privy, for sure, but there's nothing creepy about El Ramon or the albergue. Until I realized that Estevez was playing back a snippet of Psycho at us, I couldn't really understand why they didn't want Tom to leave them behind downstairs (a nonsense, since he was the one going alone). Now that I know that there was a real Ramon, I don't know if it was such a good thing to throw in this flight of fancy.
Other movie and theatre references / homages -
Emilio Estevez has spoken about the plot's resemblance to The Wizard of Oz. (Dorothy on a journey with three companions - Scarecrow, Lion, and Tinman - who are all hoping to fix their problems in the Emerald City). I think this might be a half truth. I doubt that Estevez was thinking too much about The Wizard Of Oz. Literature and film is filled with "Hero's Journey" plots (e.g. The Odyssey, Lord of The Rings, ) so it's inevitable that they resemble each another. The Tom as Dorothy theory might have been a joke among the cast and crew during filming, rather than a real source of inspiration.
I'm convinced that the character of Jack draws from The Melancholy Jaques in As You Like It. When the trio meet Jack, he's lost in thought in the middle of a field - like Jaques who gets lost in his thoughts in the forest of Arden, Jack is introduced to us through an "almost monologue" about all the metaphors of the Camino - very much in the style of verbal prestidigitations of Jaques. (e.g. The Seven Degrees of Lying, The Seven Ages of Man). Apparently the part of Jack was originally written as an Englishman but James Nesbitt was excited about the film and asked for the part. Estevez decided not to ask Nesbitt to play an Englishman, but to have him do the part in his own voice.
Now that we've found (almost) all of the locations, how about finding all of the artistic references? We could map the Inside Camino of The Way.