I'm using a GP5 Black which I'm not real happy with, I'm probably going with a Sony next time around. I can usually get a day out of a 64G card filming a 1080P/45FPS, which is my DS setting, a good compromise between somewhat decent slow mo and fairly long filming time. I switch it off sometimes so that makes the cards last about a day. I considered some kind of external storage device like a big SSD with a SD slot but I've not really looked into it seriously. I'll just pick up a few more cards since they keep getting cheaper and I don't do these rides that often. The other thing to consider is if you're reusing the cards and something happens to the SSD you just lost the majority of your footage.