There's got to be a way around a diet of grapes (when they grow) and mushrooms (when they appear). I can't get my levels up high enough to sustain them when I'm gone. And sometimes my food count will be 12 and there are no mushrooms for long periods of time.

Is there an approach to villager jobs or something or a spoiler that I've missed. This is most frustrating.

Honestly, I've found that it's not really possible to keep a new tribe running from the beginning without pausing it while you're gone. Try pausing if you have to leave, until you get your tech high enough to get other food sources.

Actually, mushrooms appear more often in VV4 than in any of the prior games. As Krystal said, you have to pause the game and "babysit" them in the beginning.