My main concern is the interest rates being so high now as to whether what I'm hoping to achieve is really even possible. 

Question: Should I collateralize the loan (if using private or hard money), or rely on roll-over loans (to maximize the lower points and 3-4% rate)?

Quote from @Scott Mac: It might be the investing environment.Right now we have a different interest rate picture then we had a few years ago.

Quote from @John Warren: @Mordechai Chaimovitz cap rates and NOI are commercial real estate terms, and 1-4 units are not really valued in the same way.

I am seeing interest rates start in the mid 6% range for foreign nationals here in Florida.

If rates come down (most likely not in 2025) you can refinance or just shovel cash-flow and pay it down quicker. 

Interest rate- prime plus? 

Many of these lenders allowing 2nds behind them are more expensive capital (10's - 13's in our current market [high rates - but now showing signs of coming down]).

@Tom Rairdon If you’ve owned your short-term rental (STR) for over a year, it likely qualifies for long-term capital gains (LTCG) treatment, taxed at lower rates (0%-20%) compared to your 33% ordinary income bracket.

Check their occupancy, nightly rate and amenities.