Overheating cooling solutions?

With the One R's overheating issues limiting the otherwise continuous recording capabilities (over 6 hours at H264), what are your cooling solutions you have?
I've seen people using heat sinks attached, but even those extend the recording time to barely under an hour of continuous shot.
Do share them here!

Anyone willing to do a test of having the One R submerged underwater to see how long it can record before it reaches the limit?
That is assuming it does overheat underwater!

I am thinking of having a peltier cooling system for the One R, but that will need quite a bit of studying the One R's design before I am ready to try it on this baby.