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.  

Then, with your next investment property, ad a new "Class" for that property.  

The lead was for a 12 space trailer park in Ada county idaho.

These will be less expensive options but be aware that the municipality might be asking for more.If the municipality is asking for zoning issues, ADA requirements, historical items or design changes, etc. then get an Architect.

I'd ad a nice striking chandelier ( not white) with multiple bulbs new table, similar to what's there now. 

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

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

Read ADA.

One board member is concerned that doing this would change our HOA from being non-profit to a for profit business and would require us to become ADA compliant (historic building that does not have elevators), pay extra in taxes, higher liability, etc.

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.