However, a DBA is not a "legal entity" and it really doesn't provide any anonymity. 

If you are potentially going to violate the rules I would just ask anonymously. 

Even if someone called in an anonymous tip, I doubt they would even follow up on it.

Would the government allow such a practice to be legit even though the owners of the property could be virtually anonymous?

Hotels do not have to release the criminal activity occurring in their properties but my guess (and this is a guess) is that on average there is more crime happening per room in a hotel room than an Airbnb rental simply because you can have a lot more anonymity in renting a hotel than a profile and review based service like Airbnb. 

An option is that you can create separate entities for the JV agreement (provides asset protection for both of you individually)...then you can hold the property in a land trust with you two both being the hidden beneficiaries (provides anonymity - folks don't know who to sue).  

If they have too many, I may forget to anonymously e-mail them back.I also jacked up security deposit requirements for everyone, as if they have an animal or 3.If no animal is involved, I have the right to reduce the deposit requirement. 

And maybe, I don't know, I could get the liens knocked down by an unspecified amount, which was told to me by an anonymous city employee IF a judge approves.  

I've come across rape, murder, child porn, kidnappings all facilitated, anonymously because of digital currency.

As a landlord you have no reason to interject yourself- all it does is open you up to more issues than it will solve.Encourage your tenants to call the police next time they hear something, they can remain anonymous if they wish.