With Pour Time Sideways and Dream of the Untouched Land could you use "skip actions on one board" on the "extra time" board (the board that Fractured Days' moved presence to)?

Yes. Dream of the Untouched land skips all Build Cards and "Each land"/"Each board" Adversary actions on one board, even if that board has had Time poured to it.

If this proves horribly abusive it'll be revisited, but that doesn't seem likely, it's pretty niche.