Good Evening Everyone, I am looking to sell my first land investment through a seller financing deal.

@Bruce FosterFirst check local zoning and land use restrictions.

Real estate is so localized, asking a broad question like this is hard to answer and no one has that crystal ball. 

There are feuds going on in every class of neighborhood over "Carl's leaves landing on my property".

I have a park with some extra land, I can explore this idea too. 

The property owner shall provide evidence that adequate parkland, fire service, sewer, streets, and water are available for the accessory dwelling unit based on standards and thresholds established in the following:a. 30% of Park Land Dedications and In-Lieu Fees as computed per Chapter 18.64 of Title 18 of the Buena Park City Code.b.

You cannot depreciate the land value. 

Excluding land, tap fees, & engineering, etc.: about $135 sq foot.

I believe they looked into zoning at one point and it was approved and now I want to look into building with my parents on their land.

If they want a high down payment then I point out a bank will finance repairs so a land contract may not be as beneficial to me as I think and again ask for better terms.