We did that on this deal and made another offer, at that time the seller finally countered and we were able to work out a deal.

It would be too advanced and capital intensive for the beginner state I’m in now.

As a beginner investor in the Chicago area, it's really cool to hear about creative deals that work out like this near the region.

For the rent repayment work out a payment plan as to how much they will pay you back every month over the next XXX months.  

The numbers work out much better for us. 

Whatever he would agree to, obviously less is ideal for you, and then workout a 3 or 5 year amortization at an agreeable interest rate to give you room to run it for a few years while paying it down, then a refinance so he can cash out and you can get long term conventional financing locked-in.

The son lived on his own at some point, then he moved with them prior to moving to CA, things didn't work out, he moved back in.

@Erik Smalls per the article you need to work out a payment plan with the IRS, and it will likely still be a factor for your DTI ratio. 

I would say if there are no significant negatives, why not give it a shot, you can always change directions and sell if it dosnt workout, right.

That might be the move for me, which of course will be dependent on if I find any deals where the purchase price and the cash flow calculation work out.