Any advice from the Boston area is massively appreciated, because I know this is an investment property, not a homeowner special. 

During periods of heavy rain and high heat, this place EXPLODES in growth rate, just a massive difference from what you get with less precipitation and cooler temps.So even though I make arrangements with my tenants to cut the grass at my places, as the self-managing landlord, I still drive around every week and more frequently during rainy/hot periods and  and monitor what's going on.

One thing I will mention is that you should go more 'retail' with your contractor as mentioned.

There are some retail centers but have to do more work than STNL. 

Zeevou is a Property Management System and Channel Manager that automates almost all areas of your short term rental business, optimises processes, and minimises human error.Smart Lock / Entry ManagementHome automation is a massive category and certainly more than we can cover here.

Those massive corporations have done their due diligence and realize that even with high property taxes, the lack of a state income tax more than makes up for it as it relates to employee salaries. 

I have the option of getting licensed with NY State as a retailer and buying direct from the manufacturers, or I could work with a retailer in the area. 

You need to be consistently taking massive action everyday. 

Got quoted 5000 from retail store.

Until the property is sold, this loan will still go against the equity though.Bottom line is this:1 -  You will be losing money on this property every month/year you are only renting out the upper unit.2 - If you sold the property, and you didn't need to pay off the rehab loan from the sale proceeds, you could walk away with at least $80k (you have to subtract closing costs from the potential $100k+ in equity)3 - You need to sell this property ASAP to stop the massive bleeding.