Airbnb is their own eco system and they're the merchant of record and take care of all payments or lack of payment.

The short answer is yes utilize a heloq if the numbers work.I would get the heloq to have available but use your cash for now do you aren't paying 8% or so for the heloq money.Then if you need cash you can tap the heloq only then.This will save you a lot on interest.You can't deduct the interest on upgrades to your primary residence until it becomes an investment property.

Value was added to the Stowers Road property through strategic renovations, including essential upgrades and aesthetic improvements.

Pick the worst house in a great neighborhood and upgrade.  

Most everything can be upgraded without gutting a home!

Well it sounds you will be on the hook for a septic upgrade.Has the township told you, you need to upgrade the tank or do they only want the drainfield inspection?

split the home into two units, upgrade appliances, add hvac, split the yard for each unit.

Or, is it possible to use a PML for just a downpayment for a turn key DSCR multifamily property not in need of any upgrades?

E.g. fire rated construction requirements on main homes, survey & soils reports, utility upgrades. 

Plans start at just $59 per month, making it an attractive option for cost-conscious sellers.LendFoundry Loan Servicing Solution (LSS): This robust software offers features like loan tracking, repayment allocation, delinquency management, and investor reporting.