I financed the best one conventionally at the highest appraised price possible, then had them carry the others at a comparable discount using some of the loan money as DPs on the seller financed properties.  

@Jason CarterSome of that time vacant was purposeful in the fact that after the tenant left, the company needed time to renovate, around 30-45 days, so I was prepared for that time, but the extended renovations into Sep and initial delay put us outside the summer. 

I'm a numbers person, so my strategy would be to create multiple scenarios and compare them side by side, looking at how long and how much it will take to move you closer to your goal.

To quickly evaluate a a deal where there is no asking price, I usually look at capex required, adjust the property taxes (based on comparable sales) and perhaps play around with the vacancy and reserves.Is there anything I am missing?

For purposes of this example, what if you identified three properties but then decided you did not want to close on any of them?

The BP calculators are a great resource as well as looking at comparable rents in your area.

This is easiest way for lenders to establish the loan as being for a business purpose.

HELOC generally with low closing cost or no closing cost but interest rate is higher compare to cash out.

If you have not, what would make you consider switching to this model compared to a more classic rental or Airbnb?

As for comparing bids, you should start by providing the architects an RFP (Request for proposal).