I personally believe that you have to read the contract. No Contract, No Binding.
This new owner already has two strikes against him, both the cost and the requested change of site. Maybe he doesn't know that your RV has wheels.....
If you together cannot come up with a reasonable deal real soon, you should change your plan and if you don't get the deposit (that you paid to the prior owner) back from someone, that is what small claims court is about.
Let us know where it ends and where this KOA is so we can avoid it and avoid the new owner.
Matt