As was already mentioned, this would be a prohibited transaction for a regular SDIRA or SD401K plan. 

My lease prohibits using the apartments for business.

Because they have previously outlawed legal city permitted STRs, it would mean nothing to me for them to once again allow non-owner occupied STRs without some assurance that at the first opportunity/whim they do not change the ordinance to again prohibit non-owner occupied STRs.They used STRs to help the RE recover from the GR but when they were no longer needed, they outlawed them. 

@Robert Smith Make sure there is nothing in the HOA covenants and restrictions that prohibit STRs before you do a lot of work, that can be an easy deal killer. 

It's not impossible but could be very very tricky to avoid creating future prohibited transactions. 

If its a duplex if you want an extra unit it would probably be cost prohibitive as they want you to retrofit the entire building with fire sprinklers.Legally you can rent to 4 unrelated people in the same unit in Baltimore city and 2 in the county.Where is the building?

In CA, several cities have placed a prohibition on all evictions.

Executive Order No. 20-06 was issued on March 18, 2020 temporarily prohibiting evictions and foreclosures.

SETTLEMENT COSTS: Buyer agrees to pay all settlement costs and charges including, but not limited to, all Lender's fees in connection herewith, including title examination and title insurance fees, loan insurance premiums, all document preparation and recording fees, notary fees, survey fees where required, and all recording charges, except those incident to clearing existing encumbrances or title defects, except if Buyer is a Veteran obtaining VA financing, those prohibited to be paid by a Veteran obtaining VA financing,which prohibited charges shall be paid by Seller.

Is funding my SDI Solo 401k with tax return a prohibited transaction?