It would depend on the location where the radar is mounted. The reason why it's 65ft at sea is because the radar is location at 65ft AGL and is unable to look down. In reality it would be 65ft only near the radar and the radar floor would increase with range.
On a land mounted radar it would work the same but there would be a lot more stuff blocking it (trees, mountains, sheep, ect..). If the radar is mounted just above tree level than 65ft would be realistic, if the radar is mounted 200ft above ground level then 65ft would not be realistic, and if the radar is mounted on the ground that it would only be able to see up and until the thick tree line.
