The private lending could finance only the down payment and the rest could come from a conventional loan, thought you may need to use a portfolio lender as some banks want you to have some skin in the game.

If your contract was just with the GC, he has skin in the game.  

You need to start saving as much money as possible so that you can have "skin in the game."

You wll certainly be able to have skin in the game.

I would like to follow the BRRRR strategy and am able to put in $15k-$20k in rehab costs (my skin in the game).

The long and short of it is, you don't need to use your money although having some "skin in the game" helps.

@Kelly AllenTheir is more than one way to skin a cat.

And by the contractor having skin in the game, the GC would not likely draw our the process and it would be done quicker with attention to the finished product since he/she will profit from a home that will sell quickly.

I've got pretty thick skin so I don't see those areas being a problem for me.  

I am a person with thick skin, and your comment did not bother me, but there are probably some new BP members who would have taken your comment negatively and it would have probably killed all confidence that they had.