It's a keeper.Step back and pretend you were buying a fix and flip or a BRRR. 

John Smith That is pretending judges cannot just change the rule.

We can exclude from DTI as indicated above, but......time travel isn't allowed and that FICO jump will not happen until after closing, so they unfortunately must get the 654 FICO interest rate or pay points to get it down to the good FICO interest rate (discount points are how someone with a low FICO can basically bribe a lending institution to 'pretend' they have a 740+ FICO for interest rate purposes).The math you do is to compare points now to buy the rate down, to six months of higher payments plus closing costs on a refinance in six months.

You think back and realize that the illegal ferrets look good now.They don't know that you know and you ignore it and pretend you don't know anything about the pets.You could say you know about the ferrets and you are disappointing they didn't tell you about them, but you are willing to waive this one lease violation provided that the ferrets don't cause any issues.I think the ferrets will cause less trouble than dogs or cats so I would try and work out something or ignore it to keep an otherwise good tenant.

So, stop pretending that you know details about this situation, that the OP never explicitly explained. 

Yes, as @Nick B. explained, but put another way, just pretend you are buying the property with cash, and no loans.

Half the time they just make stuff up and pretend it is the law.

If there are any local properties that compete with this one, call them up and pretend to be a renter, and ask them their rents.  

I am going to assume he will do the work.Let's pretend you both split the cost 50/50 and he does all the work. 

The point to this discussion is the other guys that pretend to be buyers but when it's time for them to put money where their mouth is they all of a sudden can't come through.