Since I stopped marking my strip I don't get uninvited guests. I put up a windsock when I'm using it and thoroughly brief anyone flying in (Google Earth is a great help for that).
Four years ago (when I still marked it like a mini Luton) I found a Robin parked there one Friday, I saw the pilot when he went to leave on the Sunday, He'd just flown in on the Friday, spent the weekend at a wedding and was ready to leave, having upset my local noise complainer. Doubtless he's still visiting private strips, I just hope he calls them these days.
SND