"Key Principle"/ "Key Partner" How to structure a deal?

[Fernando Tello]

My family and I are looking to start a new build 32 -multifamily in San Antonio Tx.

We already own the land free and clear, permits approve, already have the contractor in place etc... we are now moving the the financing piece, which I need some advice on. 
My family and I will be putting between 40 - 50% down payment in order to mitigate the risk of high interest rates, but the feedback that we are hearing from the banks and institutional lenders is that we "need" to be able to cover the payments for the loan with our current income (not considering the asset's stabilize income), which we don't. 

So the two options they are giving us are: Either you bring more equity into the table (which at that point I would be better of building it in faces and remove the lender) and/or bring in a key principle/key partner. 

I would love to connect with someone who has used the Key partner strategy to finance his/her deal, because I don't know what are the best practices on having a Key Principle. How much would you pay him/her, is it upfront or equity in the deal? How should I vet them etc... 

Any and all recommendations are welcomed! 
Thanks in advance!