Everyone in this thread is talking about traps and barriers, but if it was my land, I’d set up a gate and toll booth. all-day mudding pass. But it’ll cost you $100 to get your mall crawler unstuck. Do that a few weekends a month and it could be a seriously nice side hustle.
Nails could get you into a dicey situation, legally. Generally speaking, you’re allowed to take reasonable steps to protect your property. However, you are generally not allowed to create “traps” or similar devices specifically meant to injure or damage a trespasser.