Not OP, but the obvious issue is that with very large offsets the certificates all look like they've either expired or are future dated; either way they're not

Not OP, but the obvious issue is that with very large offsets the certificates all look like they've either expired or are future dated; either way they're not accepted. I had a laptop with a dead clock battery for a while; I would sometimes fumble the time when booting it and would discover the mistake when I couldn't load my webmail or Google. (Also, the filesystem would fsck itself because it was marked as last fscked either in the future or the far past, but I didn't always notice that.)