If your project incurs losses, they can help determine if those losses offset your other income or if they are carried forward.

I've sent letters to the owner on tax roll.

Additionally, they have another property which has appreciated in value, carries low interest rates, but has negative cashflow and essentially feels like it just locks money away.

Hopefully the first letter and threat of eviction record will scare them to leave, or it could drag out for months.

@Grant Shipman, I will say, I have not explicitly seen anyone violate these rules (that I know of), but more commonly there are a lot of people who have comfort operating at the margins.I.e. compliance officers/attorneys that stop at the letter of the law may say: "investment manager X, you can advertise your company all you want.  

This option is ideal for penalty-free investment but comes with added complexity and strict IRS rules.Alternatively, a 60-Day Rollover allows you to withdraw funds and redeposit them into an IRA within 60 days to avoid penalties, though it carries the risk of missing the deadline.

Appraisals, Lenders and Rates : Beyond the transactions that were literally in process (sales, listings, leases, seller carries) are properties that remain amongst vacant lots.

There i a bit of research that needs to be completed early on in order to get a good judgement on the feasibility of this; from there, the "Official" way to ensure you could pursue this would be to request a "Zoning Opinion Letter" to receive an Official decision from the Department of Zoning in order to ensure this will not cause any issues during your permit review. 

There are not a plethora of 'home run' STR's that are going to return in 2-3 years but there is significant value and definitely properties that will return 20%+ COC and definitely several dozen that are obvious values in their own right, and will absolutely carry all operating costs. 

There are lots of folks Bigger Pockets who feel they have to carry a gun to show vacant units.