I was honest with her and told her that I haven't dealt with this before and that I would check into it.The property she occupies is a 900 sq ft 2 bed 1 bath with a family room and a non- conforming "office" in the basement with a single attached garage and a large shed in a fenced backyard.

I am looking for a loan for that property but it is a little bit of a "non-conforming" property and I also don't have the 20% down for a conventional.  

List a county or two, and I'll post the non-high balance conforming loan limits for 2, 3, and 4 unit, in said county. 

Talk to your lender about what this looks like with actual numbers.You will not be able to use all of the income from the Bountiful property for two reasons: The fifth unit does not comply to conforming 1-4 unit guidelines for conventional and FHA loans.  

Using the tenants references and work or income conformation are the best methods.

If, on the other hand, you plan to do a bunch of deals with your partner, it might be a great idea.The reason for this is that, on a fourplex, you can get a 1-4 unit conforming 30 year fixed loan.  

They, like most cities, require you to conform to their terms and offer forms.

If your livelihood in part rests upon access to conventional conforming mortgage financing, why aren't you guys checking in with your go-to mortgage gal or guy with your CPA-prepared-but-not-filed "rough draft" tax returns and business structure PRIOR TO switching everything up 180 degrees on us at the last second? 

Then take it to an experienced real estate attorney in your area to make sure you're covering what you need to in the document and to make sure it conforms to the laws in your area.

This assumes you have that FICO and reserves.Do not shop for a high balance conforming loan the GSE's are price crazy for those sold to Fannie and Freddie.You need a broker with options at fifty "shops" Don't let everyone pull your credit- provide the report, the w-2/paystubs and bank statements then someone can tell you on the phone what they really can offer and how many days of rate lock.