To restate, I wonder if it is feasible to pre-qualify prospects financially and criminally before touring.

Get a great realtor who knows and understands what homes might qualify for FHA and which might not. 

Rent out all units temporarily so you can qualify for a DSCR loan.

If they're not familiar then it's your chance to get your foot in the door by bringing 1031 education to them.It's been a few years since I checked but at one time NAR showed statistics that of all the transactions potentially qualifying for 1031 exchanges, only about 10% were actually handled that way. 

Any of the above kills the STR loophole under this "substantially all work" option for material participation.Is there a way to qualify if all my outside help was a cleaning lady for 2 hours?

Scaling with Business Lines of CreditAs your business credit grows, you’ll qualify for larger funding opportunities such as:Business Lines of Credit (LOCs): Flexible borrowing for down payments, renovations, or operational expenses.Unsecured Business Loans: Access up to $250K or more without tying up personal assets.These financing tools allow you to scale faster while keeping personal credit utilization low.5.

Most DSCR lenders will require a minimum of 90 days seasoning to qualify for a cash out refinance on the new appraised value. 

DSCR loans definitely seem like a good tool for scaling, especially with strategies like BRRRR where cash flow is critical since it doesn’t rely on personal income or DTI, making it easier to qualify while keeping cash flow positive.

DSCR loans are easier to qualify for when the asset values are a bit lower and rents a bit higher.

Primary Residence is taxed as short-term or long-term capital gains on sale and it may qualify for Sec 121 ExclusionIf you are classified as a Dealer you will pay ordinary income taxes on sale.