So I went to this Spanish language meetup group that happens once a month and, wouldn't you know it, I had the oddest experience ever. As I wrote to my friend in an excited email afterwards, Hablaba dos horas con un tío brasilero que me hablaba solamente en portugues mientras le hablaba solamente en español, y nos entendimos!!! (I talked for two hours with a Brazilian dude that spoke to me only in Portuguese while I spoke to him only in Spanish, and we understood each other!!!)
The only lie there, is that I only spoke to the tío brasilero for, like, one hora and not two... but sometimes I wind up messing up the simplest parts of a sentence (like the truth, facts, my name, etc.) while I concentrate really hard on not screwing up the rest of it.
But the real good news here is that I, by some miracle, understood some Portuguese. It sounded like what might happen if someone learned Spanish by reading lips only... and then proceeded, without ever hearing it spoken, to try and put their own sound system to it.