What are the risks of signing a six-month lease agreement in Thailand while on a Non-Immigrant O retirement visa if my extension is denied?

Hi All, My wife and i are both coming to Thailand on Non immigrant o retirement visa from Australia 90 day. Our plan is to extend to 12 months once there. We are aware we need to both open Thai bank accounts and deposit 800000 Baht which is fine. I am told to open bank account we need an address and probably a six month lease agreement. My only concern is what if we sign a six month lease agreement and then our extension is denied? Could this be a possibility of happening.