I wouldn't worry too much with memory capacity. Cards are cheap and tiny; get/carry a few.
I usually don't run my cam(s) the whole time I'm doing a century. It's off most of the time; I
switch it on if something interesting is coming up/happening:
Experimenting with this cam right now; 4K/ultra HD capable, waterproof, lots of mounts included,
comes w/ 2 batteries: