It is a 200K line that fluctuates depending on whether I have a flip on the go or some other short term investment. 

That's mainly because AirBnb hosts will fluctuate their prices with demand.

This loan type can qualify you right out of college with your salary but fluctuating income they would need a 2 year history to even use it.There are other loan types that are sometimes called "portfolio" loans. 

There are legitimate reasons for taking this route, like if you are a high-earner and just need to "park" cash in a safe investment in exchange for lower returns or perhaps as a hedge against vacancy, rental market fluctuations as the rental demand in these areas is limitless even in challenging economic environments. 

Where I have extreme difficulty getting approved for anything at all here in Colorado, in Norfolk I can use my savings for a 20% down payment on between 2 and 4 units.I understand Norfolk has a few quirks, such as flood zones, historic districts, and crime rates that really fluctuate from one street to the next.

Along with the hasel/work/headaches, C class doesn't  fair as well in market fluctuations.

Taxes fluctuate yes, but not to the degree you are making it out to be.

The max purchase amount and max rehab amount will fluctuate respective of each other for each project we undertake.

The market fluctuates whereas tax appraisal does not fluctuate in the same way.

You will, of course, find better rates with certain lenders at certain times, but everything is subject to fluctuation.