Other than cutting down the trees, you give no mention of what else might have been discussed. If trees were the only thing mentioned to him and he followed through on that then you have to equalize the agreement. Four acres is rather small for multiple people and he is likely going to want to hunt again at some point, even if it's next season. You need to tell him the offer is not open ended if that's the way you intend it.I would give him maybe 5 days of hunting or 1 kill. Ending w/whichever comes first. I would also have him sign an agreement stating that he hunts at his own risk and you aren't liable for any injury that could be suffered.
OK, they were large. You know the effort each of you put into clearing them, so negtotiate well. Good luck.