And you will need a great generator because load shedding, and armed guards, and great security, attack dog's, at least 5 or 6, and bullet proofing on your auto is a good idea but side skirt flame throwers has always seemed a bit over-kill to me. 

I also make the Guarantors go through the screening process (background checks, proof of income, etc.). 

The pro of a cost segregation study is that is accelerates the depreciation into the earlier years.

I am aware that Airbnb and VRBO requires city license "proof" in order to list on their website.

Here is one proof point.This past week a friend of mine was putting an offer in on a Midwest apartment portfolio.

I send it with USPS proof of delivery but no required signature verification.

Get proof of all income.

The underwriter will need to see proof that these gains are consistent with past income and not one-off events. 

For example, if a parent co-signs for a child but the child  graduates, gets a job and starts paying the loan that debt can be excluded from the parents DTI as long as there is proof and the payments from the child have been on time. 

If the proof is there, then discuss with the tenant about why this might be happening.