property line - what would you do?

[wildchild]

so here's the set up:
bought my place 3 1/2 years ago. realtor said prop line was the poles on the corners. ok.
guy who owns the land around me rents it out to a farmer. right down the line between the properties is a trail that they use to get the tractors in the fields.
when we first moved in I asked the farmer's nephew 23 yrs old or so, not to cross my land with implements. told him i was going to put trees around the line anyway so he may as well get used to going around. soon after i caught cutting across my yard with a pick up truck. he claimed it saved him time not to have to make the corner around the pole.
I was pretty understanding when they brought in trailers and what not but not a pick up. beside normally they would just nick the corner, he was cutting right through the middle.
so this spring I put in the trees. he started whining about the turn to the field. got me to thinking, I don't want the trees to close to the line so I pulled out the plat of my land. hmmm it looks like john farmer may have moved the pole quite sometime ago and everyone has let him use what is now my land for his trail.
so here's the question, should I get the land surveyed properly and then make him move his trail, or should I just let it go, or should I make sure he is aware that he is using my land but still allow him to do it.
I am not really doing anything with that little strip of land, although I could have put my trees further over.


what would you do?