Logically the 800k has to remain in the bank and so to change to registered income basis you need to tranfer 65k every month including the months when the 800 portion is tied up.
Correct me if necessary I see the problem being late application for a renewal is 7 days. Day 1 is 28 Oct and so last day for late renewal at Thai immigration is 3rd Nov. So have to start again with new visa.