DSCR loans let you qualify based on the rental income of the property rather than traditional income verification.

The buyer is qualifying for the loan just as if he were the originator of the loan.

If down payment is your one issue with qualifying there are down payment assistance programs available. 

Pilot a unit or two with this renovation spec and see how much demand you get from QUALIFIED applicants.  

For the financial side they hire third year financial analysts (3 years removed from college) because they cost one quarter of what a qualified employee would cost.  

The problem (as you have cited) is trying to understand what you need (you don't know what you don't know), where to get it, qualifying its source(s), and the validity and usefulness of all that.Pardon me if I've gone into this too much, but I meet many people with the same concerns that you are voicing and this is offered, as much as possible in direct response to your post.Please feel free to contact me if you have any comments or questions. 

What I take some issue with is the techniques that guru's use to up sell and so on .. and they do nothing to qualify if the person paying them if the program does not work they are now into debt to the eyeballs and so on but then again who are we to say at some point.. think of  Hewlet and Packard they went into 15k worth of debt to start HP in late 40s or early 50s and that was a ton of money then :)

The building was vacant as we are remodeling the first floor and had just finished painting the 2nd and 3rd floors and were in the process of qualifying tenants to move in the following week. 

I highly recommend a well-qualified REALTOR who works with investors and knows how to help you best.7.

Going to depend much more on more details / your personal situation - all things equal you will probably get better rate/terms on conventional if you qualify for both