Follow up air tests came back perfect, and we now have what looks like a brand new house rented out for an extra $200/month.Summary: tenants caused a mold issue due to misuse of the dryer.

Refinance your rentals and reuse the cash.Add a Business HELOC "Line of Credit" on the extra equity. 

I'm speaking as someone who has earned freedom of time (which I value more than money). 

Pay extra towards the principle on your mortgage every month.

No, not even if you are paying all cash like some people would incorrectly say.It's entirely possible to earn a double-digit IRR on a 5-cap property. 

She explained that one of her investors pulled out, which is why they are short of the $12K, and they do not want to go back to the lender for the extra amount.The margin on the flip is large enough to where she can offer this crazy return.

You have ~60K extra that either becomes an emergency fund or toy fund :)With a HELOC, it is unlikely that you will get anywhere near that LTV.

Doing so will likely eliminate all extra cash for several years, keeping me from investing.

Even with the extra village tax, I like the walkability and village feel.

If you are comfortable with a property a plane ride away then your predicament is just a math problem to determine where your money/ equity earns a better return.