I own a cleaning business and thought I would comment. 

If the ADU you're proposing is the make-or-break between this deal penciling out or not, AND if it is pivotal for your plans that it be the height that you are planning, I would personally advise you to abandon this deal. 

I will not be conducting any business in MA just collecting checks as I will have a property manager managing the property in NY.

Finally, getting started on my own business.

It's an unnecessary expense to operate the business.

These are advantageous as they look mostly at the asset's for the loan not necessarily your personal statements as much as conventional loans. 

For cash flow in the area STR's are a great strategy that my business partner and I have found to cash flow well.

To date I've been able to account for smaller expenses by tying them to a specific property if for example I'd purchased an inexpensive hand tool for a specific project on that property but I don't think that would be the proper way to account for more expensive tools that I bought for the overall business like a new lawn mower or something. 

@Samantha Soto  We have done this before but honestly I would run your business now as if you would run it with 20 properties. 

Communication, photos, and documentation is everything in this business.