This is a good question and one I would recommend speaking to an STR knowledgeable licensed tax advisor on. 

A lender would have to sue to unequivocally establish lack of compliance. 

Getting into multifamily will be much easier after your first deal and your local team is established! 

What I was told if that I shouldn't pay down my mortgages if I can get a better ROI somewhere (I'm not a CPA or financial advisor, just sharing what I'm doing). 

-Online Template-Financial Advisor with Strategic Partner-Estate Planning AttorneyNo right or wrong just more choice now.  

Smaller, older homes tended to have higher price per square foot.Most homes sold were built between the late 1950s and 1980s, making it an established neighborhood with older housing stock.

I established a  mgt entity for leases, deposits, income, expenses, but never held any of my dozens of residential rentals in LLCs over my 21 year run.It's just tougher to get good mortgages and insurance. 

I think it takes a couple of years to establish a relationship to trust someone to do any type of business deal. 

Whatever it may be, establish the purpose of it.3) Do a study of what you're trying to get into and most importantly trying to avoid.

Here are some steps you can take to get started:Establish Your Goals: Establish your financial and long-term goals while investing in real estate.