I have friends that lived and rented in Bariloche long term without having to provide a guarantor. Look at the properties on Airbnb and some are affordable. Just negotiate something with the owner/manager and they probably would work with you. The owners know that the risks of renting long term to a foreigner are MUCH lower vs. renting to a local. And still if possible go through Airbnb's booking platform. I know that goes against the intuitive nature to just deal directly with the owner but you have many more protections going through a platform like Airbnb.
First of all, even if you do a long-term lease on Airbnb, they only pay the owner one month at a time. So if problems come up then you have protections with the owner either fixing it or being able to leave. My friends that lived in Bariloche didn't have problems negotiating something with owners long-term. Typically they have two high seasons. One in summer and one in winter during ski season. But other periods they are relatively slow. So I'd think most owners would rather have a guaranteed 2 year lease.
If you're trying to book a nice furnished property you're probably going to be out of luck as they can make more during high seasons renting it out short-term vs. a severely discounted lease. But a lower end property you shouldn't have as much of a problem.