He was open and honest and said that he had bad credit but I was shocked when the application came through and he has $40k in collections as recent as March 2018.

You can find commercial departments at local banks and credit unions as well.

I am buying homes that wouldn't pass appraisal standard for the low credit/low down loans and cleaning them up and rehabbing for the first time home buyer with marginal credit etc..   

What should I do with a potential tenant buyer who says he has up to $50k to put down on a property but he has very little credit so he probably can't qualify for a mortgage in the near future? 

Try to have your personal debt under control, have a good credit score and understand you will need some cash and reserves the amount will be determine by your market.. .

I would go through my credit union with again a 30% down. by then I would have the downpaymeny as I currently have all of my capitol invested.how would you structure this deal. the seller is looking to get the money sooner rather than later.I can figure out the expenses and income. however I can provide it if need be..thank you!

Problem my debt to income is through the roof and I can’t count my wife’s income because her credit score isn’t good enough.

Typically, the Canadian tax will be greater than this and you can get it back with a foreign tax credit filing - so you are NOT double taxed.You can also charge active management fees from the Canadian corp against the C-Corp and withdraw funds that way. 

I have a potential partner for purchasing 5 SFR who will bring capital for the purchase and the deal, but does not have the credit for loans.

By the way, broker thinks we can get a $10k credit at close for a new roof needed.