Well I put the towel over the box once more, and turned it on.. then forgot about it for nearly an hour. Came back, turned it off and left it until the next day. I played with the console standing vertically and it crashed after 5-10 minutes, I then laid it down horizontally and have been able to play for 2 hours at a time, about 3 times!
I'm trying to play as much in one session as I can, as I feel that the more I turn it on and off, putting it through heat cycles, the more likely it is to RROD again. I'm sure the towel and oven trick only work so many times?