They are two of the largest wholesalers in Mobile and they usually have a couple of new properties every month. 

My background...topped out sales compensation plans in both companies I did sales for, including in a global role for a anti-virus software company, selling to the world's largest telco's. 

"Mobile homes  provide the largest source of unsubsidized affordable housing in the United States (CFED 2016).  

The second appraiser did not use the same "distinct marketability" approach but instead simply went a little further out geographically to get more comps.

Killeen is the home of Fort Hood the largest Military post.

The distinction would be if the income would not be used at the purchase of the property, lenders on traditional products will not use the income from legal units, because that income can not be relied on. 

@Dennis Rogov take a look at facebook groups: "Travel Nurse Housing - The Gypsy Nurse" is the largest one for traveling nurses as far as I know: 130,000+ members. 

HOA or simply 'agreements' (this is usually a state regulatory guideline)....and I guess third is how do you make sure you get FHA approval for your association so you can sell to the largest number of end buyers (this is a federal lending guideline).You can't mix the definitions from one arena into the other, they all function with each other and at the same time autonomously.

This is what Id suggest.Figure out which brokerage has the largest market share in your market.

@Aaron White There are a lot of lenders out there that can lend on these types of scenarios. 1-4 units are in your single family home and 5+ is when you get into the multi-family with regard to distinction for loans.