All rents you get from this property has to go back into the SDIRA but if you get a 20 year mortgage (that the rent can cover) and can pay the rental off by age 65 you will have turned that $90K into several hundred thousand’s of paid off real estate.

You start by mentioning your age... you'd need everything to go just right for the rest of your life to make, best case, $400 or less additional each month net cash flow. 

Many others on here have said the same thing, but at your age i'd focus on career.

Many of us on here wish we were thinking about real estate at that age.

This comes from several data points, the first being the average age at which people are choosing to stop renting and buy their first home.

For instance, mismatched names, employment details, or salary figures should warrant further scrutiny.Urgency to Move In: Applicants who are unusually pushy about quick move-in dates may be attempting to bypass thorough checks.Reluctance to Provide References: Hesitation or refusal to provide contactable references from previous landlords or employers is a cause for concern.Cash Offers for Faster Move-In: Proposals to pay a significant amount up front, especially in cash, to expedite the moving process can sometimes indicate an attempt to avoid scrutiny.Unverifiable Identity: Difficulty in verifying the applicant’s identity through standard identification documents can indicate potential fraud.Tips to Mitigate Rental Application Fraud:Enhance Verification Processes: Implement stringent verification processes for employment, previous rental history, and identity.

Congrats on your maturity at a such a young age.   

@Polat CaglayanI've never seen a formula but here is a general rule of thumb for multifamily:The class of an apartment refers to the quality of the building, which can be determined by a number of factors, including age, location, and condition: Class A: These are the highest quality apartments, typically built within the last 15 years.

Be careful not to place your identity in your age/success in RE.

Congratulations on building such an impressive portfolio at such a young age and achieving so many successes!