How would've the existing electric, HVAC & roof REALLY affected the STR marketing & guest enjoyment of the property?

Just because that $440 isnt via cash in your pocket each month does not mean it does not exist.

Consider options such as adding to down payments, reserves, or investing in other income-producing assets aligned with your financial goals.Next StepsTalk to Lenders: Discuss your financing options with lenders, including the possibility of a cash-out refinance or HELOC on your CT property, and explore the 10% down payment product for your next purchase.Real Estate Market Research: Identify potential markets or properties that fit your investment criteria, whether for house hacking in Las Vegas or remote ownership.Consult Professionals: Engage with a real estate agent, tax advisor, and possibly a financial planner to ensure your investment strategy aligns with your long-term goals and financial health.By leveraging your existing equity, navigating financing options, and resolving tax matters, you can position yourself and your girlfriend to successfully expand your real estate portfolio this year. 

I feel like this deal pencils at $365-375k but need to add a bathroom, redo kitchen and existing bathroom, close in garage port for more sqft, + cosmetics and new appliances.

If the lender won't budge you can always refinance the parcel containing the existing home and remove the developable parcel from the new loan request.

Hire a Architect to provide drawings with a lot of details such as existing house elevations and floor plan, proposed elevations and new floor plan, roof, wood deck, addition, etc.

In larger mutlifamily properties I typically increase my existing expenses (non-mortgage expenses) by the same growth rate as my revenue.... assuming I have up to date and accurate existing expenses.

You made the same mistake I did which was to agree to renovate an existing space that someone was living in.

It doesn't exist yet. 15% down will most likely be at a high 8% rate and you may get an LTV reduction with it being a short term rental. 

This policy will provide additional coverage above what your existing policy covers.