This is a lovely idea for a challenge.
Are you aware of the smiliar Earth Pieces of The Boyle Family (boylefamily.co.uk)?
An extract from their methodology "Manual for the Journey":
The objective of this Journey will be to make multi-sensual presentations of 1000 sites selected at random from the surface of the earth. Between August 1968 and July 1969 blindfolded members of the public selected these sites, initially by throwing darts and eventually by shooting them into what turned out to be an enormous map of the world. However big the map, the dart point inevitably covered a considerable area and so could only be an approximation of the site. A larger scale map of the area covered by the dart point is then obtained and a further dart is fired to select the actual spot. Perhaps if large scale maps of the area are not available it will be necessary to draw one. On arrival at the actual spot an area 6 feet square is selected at random. The method of selecting the actual square varies, depending on the terrain (e.g. on a flat treeless piece of ground a right angled piece of metal thrown into the air will determine one corner when it lands, and the lines can be produced to form two sides of the 6 ft. square. Vertical or suspended elements on the site must be included in the total area from which the selection of the final square is made). Everything else about the Journey must depend to some extent on what is possible in the realm of equipment, materials, transport etc. etc. And the size of the finished work, though as near as possible to 6 feet square, must depend on the difficulty of the terrain it has to be transported through. But nothing must be allowed to affect the random selection procedure. It may well be that on the site, geographical or botanical or animal features will pose conceptual problems. These must all be dealt with in a random manner that removes the possibility of personal subjective selection of the site. The arrows on the detail maps in this atlas give only a rough approximation. In every case a further dart will be thrown at a large scale map of the district to select the actual spot.