Get a quote for the cost to completely renovate the area they might use-- remove whatever rock they put down, decompact, restore topsoil, re-seed. For a general idea, I have a current estimate for restoring a 4-acre area that we plan to use as a laydown yard (it’s currently farmed, we’d be putting down 6" of rock to accommodate 200+trucks unloading material on it. That restoration cost, for us to return it to original arable condition, for 4 acres is $175,000.
THAT’s your number-- not a lease payment, and not $1k an acre purchase price–because that’s what you stand to lose. Contracts are fine, but you have to be prepared to enforce them, and the counterparty needs to have the financial resources to be worth going after. I’d bet a mint that this logger does not have those resources to fix your land when the truckers ruin it. So when you sue him for breach of contract, it’d be a hollow victory because you’re still stuck with ruined ground.
It is not your problem that this neighbor bought property that does not have sufficient access for him to use it as he wishes. This is not your problem, and that does not make you “not nice”.
Name a reasonable price to sell a permanent access lane, and just let that offer sit there until it becomes worth it to the neighbor.