While they are indeed somewhat arbitrary, they provide a straightforward framework to filter out properties that are unlikely to meet my investment criteria.1% Rule: This rule helps ensure that the property generates sufficient rental income relative to its purchase price.

My CPA says it is sufficient for tax purposes to have records of invoices from the PM to me. 

This alone MAY be sufficient for you partner to believe that you will NOT “do nothing” and he may at this point reach out to you.2.

If there is so much money invested in DST's, can one reliably say that sufficient number of investors are profiting?

The way to avoid this is to have sufficient reserves.  

If you can pay less than rent, and if you have sufficient reserves, that's the way to go. 

Lastly a Heloc will "Never" act as an asset or PITI reserve so if you fail to have sufficient funds required in reserves (Cash) then your will not buy multiple investment rentals.

I’m just joking around mate hehe  I figured as much but I think I may just not be sufficiently accustomed to Aussie humor lol

2) PS specific home - We looked at a few and were intrigued by one that is a 3/2 (plus self sufficient ADU, former garage) with a nice pool, yard but 2/2 on city records.

You should be able to find some good options on here so long as appraisal is sufficient and DSCR min is met