possible solution for over heating phone during extended game play.

[TB-1599]

No I don't know how portable this would be. But if you do most of your Gear VR time at home this could be a solution. I saw this while watching a video review of a Gear VR game. I am very, very tempted in picking this up...
Amazon.com: Pyramid USB Multi-Angle Phone Cooler Titan TTC-NF02TZ(BB) Black: Cell Phones & Accessories

 

[km04]

So this is connected to your phone while it is in the Gear VR? Not sure how that would work.

 

[TB-1599]

So this is connected to your phone while it is in the Gear VR? Not sure how that would work.

It looks like it suction cups to the back of your phone....It runs off of micro USB so you could prob use a back up battery phone charger. (like I said not the most portable solution but good for extended game play)

 

[kendo nagasaki]

ive been looking into micro usb fans rigged up to portable usb charger, thats if there`s clearance between phone and the face plate.
Or go down the low tech solution and cut these to the right size.
https://m.icepacks4less.co.uk/#!/Reusable-Gel-Packs/Medichill-Ice-Packs