And, I have an amazing PM that charges me a flat 6%.  

It sounds like you want to work with them so just try to work it out where it benefits you both whether that's a flat fee or % of rehab costs or a % at the end.  

I normally charge about $45 per hour for my time, management and supervision on projects or a flat weekly rate that amounts to about 50 hours per week @ $45.

. $10K just isn't enough and you need to find money from others and figure out the terms so you know how to bake this into your calculations/spreadsheets accurately.

They were done as follows:1) We gave a 90 day loan with a flat interest amount for a rental purchase. 

We've also repaired rotten balconies, replaced the roof (twice) (pro-tip: pay attention to proper ventilation of a flat roof).

I think there will be some ups and downs and could stay flat. 

Many of us have tenants with a fancy flat screen TV and a blinged-out BMW who are behind several months on their electric bills.

You can absolutely find great tenants in low-income populations (about as much as any other income pool) BUT the nature of their employment situation means they are one sick kid or one flat tire away from missing rent.

That, combined with the fact that they’re taking great care of it would help justify the flat rate.