Especially when he drinks the SJ that isn't even R

Here is my personal experience. I'm what I'd consider highly functional, but not completely fluent. I learned the majority of my espaņol in both Chile and Argentina, with a bit of US education thrown in (including a short time @ Berlitz). The "ideal" in the Americas would be to learn what is considered the most neutral, which is Colombia (so they say). But nothing is really neutral.

Here is what I ended up with. More of my vocabulary is chileno, but most of my grammar is argentino, as well as the cadence of my speech. My earlier travels were in Argentina, then the ones where I really started making friends and having long conversations were in Chile, now, a lot more traveling to Argentina. Both of which have people looking at you when you speak in the US or Mexico (more in the US, than in Mexico), but you will function just fine, save the occasional faux pax because an innocent word in one country is super mal dicho in another. (A couple of examples would be the filling in an alfajor in Mexico is a female anatomical part slang in Argentina, or rush hour in Argentina would be male anatomical part hour in Chile. )

I would suggest you learn espaņol wherever you want to hang out for awhile, because if you like it, you'll be returning. And if you travel around, you'll function just fine, even if you accidentally ask for something inappropriate from time to time, or can't figure out where the food is on the highway when you hear that there are "tacos en la autopista."