This is my first time here. I apologize if my presence is not suitable and will humbly withdraw. I have 3 acres of land in the high plains desert and am looking to buy 40 more. The land is flat, to the naked eye, but when you start moving around with a gps you find otherwise. I want to make a very detailed topo map of the property so that I can better manage runoff from rainfall. I would like to work with nature rather than completely building a whole new system. My idea...may sound crazy...is to get a remote controlled car and put a gps unit on it, and drive the car all around the property to collect data. The gps would only be 4" or so from the ground, and it would be a consistent distance. On my present land, the different from low to high is about 3.0 feet. Is there a gps (<$400) that is sensitive enough to do this? The new property is about 1/3 hills, but I want to work on the small piece first.