"Shy Picker" wrote

David, there's lots of issues here. Right now, tide's running high and
tempers are not normal. Best to not destroy something that can't be
repaired later. My SIL did that. email me if you want the ugly details
(address not munged).

Anyways, best bet is they have always driven over that land area and didnt
'just start doing it'. If so, plant a few small fruit trees (assuming you
are in an area where that is an option) and put tomato guards about them
when small so they can be seen. Don't plant too close as you want them to
grow, but you can plant them close enough that a farm vehicle would have to
go around. Don't worry about the 20 ft cornfield area. Just shift back 20
feet or make a cut out for it (leaving room if it's something they need to
get a farm harvester around so they can). Tell them once crops come in,
they are welcome to pick personal consumption levels for the house and if
the hired labor gets hungry and sees an apple, it's fair game.

This is a fence, that builds a bond, instead of breaks one.