I would recommend learning how to wake yourself up whenever (waking up mantra) then you will be able to just decide when you want to wake up later and go to a different mantra.

I agree with the rest from cloudless sky, you need recall. The best thing for recall IMO is to wake up 4 or 5 times through the night. If you read all the stuff they have here, then I am sure you know of the technique for waking up after each REM.