I got more than enough up front as the non-refundable Option fee to cover all expenses and rents and to get a judgment against the Optionee.

You'll have access to owner occupied loan products, therefore saving on your down payment, typically 3-5% compared to 20-25% for non owner occupied properties.

And, the breakup fee is a non-starter.

Here are the numbers:IncomeTotalPartner ContributionsManaging Partners Debt$0.00Partners Deposits$987,459.99Total Contributions$987,459.99Operating IncomeAirbnb Income$50,186.50Square Income (Vehicles or add-ons)$6,741.04Total Operating Income$56,927.54Total Income$1,044,387.53ExpensesPurchase of propertyCost of House-680,000.00Closing Costs-$26,744.44Total Cost of Purchase-706,744.44Set Up ExpensesHouse Improvements & Care taker home addition-116017.03Adding Tiny House-52130.83Furnishings-68403.65Vehicles-43150Set Up Costs and Advertising-2339.53Total Cost of Set Up-282,041.04Operating expensesCare Takers-14535.9Additional Cleaners-1505Cleaning Supplies-2670House Supplies-1340Landscaping-4230.66Utilities (Power & Water)-8204Internet-315Pest control/fumigacion -120Pool cleaning/maintenance-2220Vehicle Gas-552.3Vehicle Maintenance and Repairs-6625.01Welcome Food for Guests-115Property Repairs-4999.64Bank Fees-1208.06Accounting Fees-1085Insurance-955.74Other Expenses-1071.2Total Operating Costs -$51,752.51Total Expenses-$1,040,537.99Net Income$3,849.54Net Operating Income$5,175.03Now 5k for an investment of 970k is not a good investment.  

Simply put the risk of a non-renewal costs more.

A special committee was formed last year, and was to hold 6 non-public meetings and then send their finalized recommendations to the commissioners in November.

I know that the general guidance is that emergency funds aren't to be invested, but given our financial security and the fact that we already have a personal e-fund in a safe, non-volatile location, would it still be crazy/unwise to invest this 15k in an S&P500 index fund in a brokerage? 

Most nearby cities are the same.Even in the Denver-adjacent cities that do allow non-owner occupied STRs, they vary widely -- some have caps on STRs, some cap the nights rentable as an STR, some cap the number of vacation rentals one owner can have, etc. etc.This is all to say, first know where you can do Airbnb, then start running numbers.

If you are open to non-traditional methods of financing, you could use a debt service loan to bypass that requirement.

That way they keep their licenses and ratings.I don't see much of a difference really.Don't keep them out as they will get increasingly suspicious and they might pull your permit for non-compliance.