One of our homes will become a rental/Airbnb property and the second home that we are currently building will be our main residence and have an ADA-inspired in-law suite for my parents.  

However, if you really like this house, you can use the wrong ad as an leverage to negotiate to lower the purchase price.

This is not really a stretch; my available units usually garner HUNDREDS of inquiries, and I usually get a dozen or two that actually get in for a showing.If they have not confirmed an hour prior to their appointment, I send this text to their phone (which was required as part of their contact information I required in the response to my ad):As I had requested in my email, you have not yet confirmed your apartment showing for this evening, scheduled for 7:00pm.

@Jesse Waters I am NOT an attorney but have had experience with ada and other protected classes.  

The closet is approximately 5x6', so I could use the entire space and ad a tub or only use part and add a small shower.  

The property is a 100 year old storefront that got an adaptive reuse into a mixed use property by adding two apartments in the vacant upstairs.The building got a full overhaul in the process including all new HVAC, electrical, plumbing, fire sprinklers, structural repairs, ADA compliant bathrooms, and new storefront facade.

There is nothing you can do about it.As for Fair Housing, my tenant’s neighbor will be protected by ADA - she has the right to move in her own house on wheelchair even after 11pm if she needs to.

ADA laws do not require it.2.Yes People can have 2 service animal's!

In my opinion, I don't think  you need be concerned about an issue with the ADA.

You're in violation of federal law with the construction as that creates a different qualification under Dodd-Frank and a 9 month balloon, predatory lending, Texas municipalities  also have predatory dealing laws, looks like you might fit there too.The "handicap" have no special provisions as a borrower, ADA has no effect in that respect.