I'm a fan of filling with ground plane. In v2, I think you should fill both sides with ground plane. If you did that, you could flip the RPI over and heat sink it to the ground plane. If you stitch the edges with via, it will help transfer heat from one side to the other.
I'm a fan of filling with ground plane. In v2, I think you should fill both sides with ground plane. If you did that, you could flip the RPI over and heat sink it to the ground plane. If you stitch the edges with via, it will help transfer heat from one side to the other.
Flipped RPi with ground plane fill:
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Ground plane stitching example: