Any excuse you give (you SHOULDN'T) will be met with challenge, bargaining, threats and sob stories.These people are wasting your time and driving away other customers in your business, and making trouble for you with the municipality, to boot.You're also being too soft and they can smell it on you. 

Sounds like a business opportunity,  once you learn Yardi, remember this, and you can have a side business teaching it.

We got approved for one Amex for one (STR) business and another Amex Blue for the other (LTR) business. 

Not someone I would recommend doing business with.

My business partner and I are in the process of ending a very successful 10+ year partnership in which we managed to build a portfolio of 50+ units through the BRRR method. 

Quote from @Derek Morrison: No, you do not have to allow everyone to view the property or apply.

I have been a Wealth Advisor for the last 9 years, and I started a Airbnb rental arbitrage business about 3 years ago. 

There are lenders that will allow up to high combined loan to values for helocs and/or second mortgages. 

Then you have to look at the density allowed.  

It just feels weird to treat it as a partnership because a primary residence isn't a business.