You can also request a security deposit for extra peace of mind. 

Security deposit amountYou can find plenty of examples by searching for "tenant estoppel certificate doc" or exchanging "doc" with "pdf" for more options.Here is an example and explanation: Sample EstoppelSome have a lot of legal jargon but this document does not need to be so detailed.

my RE income from my rentals is semi-passive of course... so less active than W2 but more active than dividends or social security.

Additionally, are you recommending that we should prioritize taking action and securing properties that align with our long-term investment strategy?

Here is my current situation - I can probably secure a personal loan for about 200k at around a 3-4% interest rate with a 5-year tenor.

Also, what’s been your biggest challenge when it comes to securing the funds you need?

And I STILL have a ways to go to get my first social security check at 62.  ;-)  I have 8 SFR, all in A- to A areas.  

The premise proclaimed at the start of this thread is simply not supported by mathematics with the exception of the specific case where the interest rate on the HELoC/secure LoC is sufficiently lower than the rate being paid on the mortgage.

Quote from @Gary Bonds: Any best practices when attempting to secure business funding from a bank, in the form of a loan or credit?

I did not read the rules around security deposits. you may be allowed to use those funds and still file a small claims action for any remainder, but I can't imagine that it would be worth it if you have at least one month's rent in security deposit.