In place of a flat fee I can see the transition being something based on referral (did my buyer agent get me a trades person, lender, home inspector, etc.

If you and another person own a piece of real estate as tenants in common then you both own real estate. 

Do you have a 501c3 that you operate under (and rent the house from yourself), or do you purchase homes with an LLC or personal name, and run as a regular business? 

Also, you don’t need a business license just to look at properties, but if you buy a bigger property, like a multi-family unit, you might need a certificate of occupancy, depending on the local rules.For business trips, most expenses can be deductible, but if it’s part personal and part business, you can only deduct the business portion.

Secondary Markets Are ThrivingOmaha and San Antonio are two examples of secondary markets where the cost of entry is still reasonable.

Do you have a personal connection to either of those cities/markets?

If you do decide to do mailer(s), then I would advise you to personalize the card and do a handwritten note. 

Here is my favorite (among several others, just as hysterical) part of this case:"...Petitioner’s testimony that neither he nor his son used his personal bedroom,living room, or kitchen for personal reasons strains credibility.

Personally (as a STR-focused REALTOR), I would never give you numbers and tell you you can hit them. 

We take a "whole person" approach.