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.
Why is land ownership so important if you can lease with 30 year automatically renewable leases and right of succession with a Usufruct that gives you the right to build or farm or anything and must convey if the tract the property sits on changes ownership?