What issues might arise when my friend extends his SETV without a TM30 filing in Thailand?

I have a TM30 question that I haven’t seen addressed before. I have a boat that is berthed in a Phuket marina on a long-term agreement and I have allowed a friend of mine to stay on it. He is here on a 60 day SETV which he wants to extend by 30 days. I didn’t file a TM30 when he arrived so what problems do you think we might encounter when he comes to extend? And any suggested solutions much appreciated.