If it doesn't really impact your land, just sell it to him an move on. Also, a consistently and frequently used piece of land for such a thing as a driveway that has been used for several years, even for far less than seven, could be ruled in the favor of the violator by a judge. They do have discretion in these things, if there was no obvious intentional misuse. If it really isn't a big deal, like blocking your view, your use, or causing drainage issues, why put up a legal fight, waste time and money, and a lifetime of sour relationship with a neighbor. In the sale, you could also stipulate that it has to remain gravel, a certain width, depth, no fences/monuments, etc., to benefit you in the sale. Just an certified appraiser's 2c...