You have to make him feel like you're a serous investor, living in his complex may not convey that but only time, relationships and persistence will get you what you want. 

I want to be reasonable, but at the same time convey that I am firm about the late payment and ensure future rent payments on time.I plan to agree to this via a legal document I found online  (I can share the link if you want and if it's allowed) called a "Late Rent Payment Agreement". 

@Brent Coombs, the deed conveys ownership while the "Subject to the existing financing" wording relates to the lien/s.  

Seller will convey using an as-is contract, clear and marketable title with a warranty deed.

Look closely at section 5.062(a)(2): “An option to purchase real property that includes or is combined or executed concurrently with a residential lease agreement, together with the lease, is considered an executory contract for conveyance of real property.”The “180 days or less” exemption exists as an accommodation to real estate brokers, because otherwise the TREC 1-4 contract could violate this provision when combined with a TREC temporary lease.Options that are not combined with a residential lease as well as options on commercial property are not affected by Property Code section 5.061.

Good question Ivan....I guess you see if their were any re conveyances filed after that date....cause once they are paid off they are supposed to clear them.  

However here you usually get your EMD back if they cannot convey good title.

An option is simply a contract to sell, no title interest is conveyed until the sale.

and find out if you can convey a warranty deed.

I have an REO under contract that I can convey to an end buyer for a possibly better deal than flipping myself.