If this is your first investment altogether, I'd opt for a more traditional, simpler purchase. 

You could rent out your current unit and buy another house hack, or even convert the whole property into a traditional rental.

I wondered if SF route might allow us to secure better terms at maybe a 4% interest rate for a few years on the funds not rolled into current $150k potentially assumable mortgage -- and in a few years we could roll into a traditional mortgage. 

Instead of leaving equity tied up in the property, you can refinance and put that money to work on your next investment.Advantages:Leverage: You’re using borrowed money to increase your purchasing power.Long-term Wealth: By holding rental properties, you benefit from appreciation, passive income, and tax advantages.Scalability: The ability to keep reinvesting capital makes it easier to scale compared to traditional buy-and-hold methods.Is BRRR Right for You?

Great news is when you get a deal there the spread is usually solid, bad news is many of the traditional marketing tactics don't work very well (at least in NYC where you cant cold call, PPC & PPL is really expensive and I don't know anyone who does well with direct mail).

Based on my knowledge of the market and similar properties I think these are at, or near, 2X market rent.I've use a traditional bank to finance the purchase of each of these buildings - using a traditional commercial real estate loan.

A traditional IRA pays taxes when you withdraw month at your normal income tax rate which is generally higher than the normal capital gains rate.

We also give full 2.5 weeks off during the holidays because family and Christmas traditions are important to them.

For buyers, down payments range from 20-30% and adjustable rates are generally about 75-100 basis points higher than a traditional mortgage (no fixed available).http://www.vacation-finance.com/index.htmhttp://www.dotcomdesignstudio.com/gallery/patrickmorrissey/fractionalfinancing.htmhttp://www.firstfractionalfunding.com/

I've done it the traditional way of using my credentials; credit, job/salary, personal info. to getting a FHA loan.