So the underwriter looks to see where you are now with ALL sources of income and debt vs where you'll be after the purchase  and applies their maximums appropriately.The brokers I have worked with would not allow the 43% DTI as in your scenario, @Justin R.So the key is to either buy a rental such that it does not send you over the maximums or reduce your other debt or increase your other income until the ratios work.  

On a recent short sale we did, there we had to sign a form certifying that the seller would not continue to occupy the property through a lease or otherwise..What is the source of this prohibition and why?  

I feel that they won't have problem paying the rent, but with utilities and all, plus food, etc..

is vulcan 7 a lead generation source that i cold call?

They got to the deal first or they "sourced the deal" as we call it in the industry.  

My previous basement tenants were vendors that sold food out on thw street.

The Gap lender's rates are typically a little higher than the lender in 1st position.Another option is to work with a lender that allows the down payment/skin in the game to come from other sources such as Seller Carry Back or Cross Collateral.

Dominik:Could you point me towards the source of that statistic: "...in Canada more than 50% of "Rent-to-own" deals fall apart"?

A wholesaler basically sources the property for an investor and receives a "finders fee" for their work once the property is closed on by said investor.

I sourced a replacement (about $50.00) and installed it in 10 minutes.