I come to you hat-in-hand, looking for the collective expertise I've come to enjoy here. 

Most S8 tenants have a history of bad decisions, often having convictions, evictions, bankruptcies, chargeoffs, collections, garnishments, etc.

I would say the cash flow would go up every year and that would usually be the case but my son will be moving into one unit probably for just the labor to rehab the last unit (collected rent will go down for a year).After that rehab is complete, at market rent I would have about $8k/month cash flow with underwriting that most would consider conservative (for example $1200/month allocated to maintenance/cap ex). 

How do you collect and is worth the time, effort and expense?

Start collecting contact cards and fill that phone with everything from plumbers and painters to bankers and lawyers. sorry this is so long and drawn out.

.), Either a US credit report or credit trade line history in your country of origin, US Entity documents (EIN, Operating Agreement, Articles of Organization,), 2 months bank statements for proof of closing, and 6-12 months reserves on top of closing costs and DP. 

You will also need SOLID proof of mismanagement, not just being unhappy. 

Then you state how that will be collected.

An 8% protected preferred return or a 10-12% target return. 3) Our passive note platform (Swell.investments) has yield from 8-20%. these are loans we have already originated and are available right now and we are happy to keep vs. matchmaking or crowdfunding where you only get to invest if the marketplace collects enough investor dollars or the matchmaker has a deal ready to fund (what you call whole trust deed investing).

I actually have done a lot of research on this because I love 1980s and 1990s arcade games and plan to collect my favorite 7-8 games eventually.