Depends on a landlor, if he is nice- no. Salary receipt can work as garantie.We don't have a garantía in BsAs, but do we need one
could pay a year's rent or two. Would this be allowed?
Yes. But I do not recomend this. The worst (and most likely) scenario your landlord will have no motivation to be nice to you- he got all the money, come on, he will try to make your life there impossible right after, to get some other gringo paying for years upfront.
If you change your mind about this place and would move out earlier -you most likely will not be refunded, at least not voluntarily for sure.