Plot plans are required for all Additions, New Construction, Sheds, Pools, etc. These plot plans are a requirement of the building code. The plot plan is required to be stamped by a Surveyor.
Mortgage Inspection Plans - are not necessarily acceptable as a Plot Plan.
Site Plans - are not necessarily acceptable as a Plot Plan.
Septic Plans - are not necessarily acceptable as a Plot Plan.
You may need to hire a Land Surveyor to properly show what you plan to do does not violate zoning set-back requirements.