Consideration to the to lessor at the time the lease is executed for the right of succession. It's permissible and it's enforceable and it's done. If you grant the lessor 1 million baht for the right to will to an heir and it's accepted, that's binding.
America and Thailand are virtually neck and neck in national crime stats and like America there are safer and less safer areas. Corruption is a bigger problem for Farangs that you wouldn't experience here.