I can afford to have the unit empty, but obviously don't want to do that, and am at a loss around what I should do going forward.

Obviously, it’s better to have the units submetered, but I know sometimes it’s cost prohibitive.

Quote from @Colby Easterling: Quote from @Joe Villeneuve: First lesson, which maybe should have been obvious (is now).Garbage in, garbage out.Second lesson.Learn before you buy,...anything. 

So obviously, there is less risk if you go for passive strategy, but that results in less cash on cash ROI. - I said I want to go for normal investment strategy.

Obviously you said you are very experienced so I'm sure thats based on that. 

Obvious, but maybe the least reliable as it is somewhat by chance.

Obviously I can't say for certain that's what happened with those specific properties but it's just a slightly different strategy. 

Although the obvious answer is to consolidate, recommend you don’t.  

The obvious answer to me is a free web based project management tool like Asana, Trello, or Freedcamp (there are many more I'm just getting started looking).

Obviously, they will pay less for these loans because of the resources they spend upfront.Most of the larger private lending firms will participate in correspondent loans.