As others have said, you need a local real estate attorney, but a land lease seems simple enough. Terms of the lease can include that the lessee pay any increase in property taxes due to the improvements, and that the improvements remain with the landowner upon lease termination.

Perhaps the trickiest part could be what happens in the event of death of the landowner, or if the landowner wants to sell the land. This can also be handled in the terms, and typically if the lease is publicly recorded it wii survive any transfer of the land, by death or otherwise.