Mark has never been stuck with a piece of raw land because he always makes the deal irresistible. When selling the land, the typical deal structure is seller financing. Mark gets an initial down payment, which will usually cover his current out-of-pocket costs. Then, he gets monthly passive income in the form of a payment based on the seller financing terms.
Soil Terrain and Vegetation: Most small landowners will prefer a mixture of hill and valley, but level agricultural land is usually more expensive than hilly ground.  However, if your property is smaller, say less than eighty acres, there will probably be a better market for the mixed terrain that includes level bottomland and forested hills.  Likewise, the best overall market exists for small properties with a mixture of forest and meadow as opposed to all woods or all field.
You can also look to certain companies and organizations that have a concentration of people that may fall in the above mentioned roles such as investment companies (i.e. Charles Schwab, Fidelity), financial advising companies (i.e. Morgan Stanley, Merrill Lynch). There may be a higher concentration of people who can both afford and want to build their own custom homes or to build income-producing properties. Try linking yourself to financial advisors who may already know of people who have these types of dreams. This isn't a comprehensive answer of all the possibilities but just some thoughts. Good luck!