We haven't been camping since DD was 4months old, but are going at the end of October. Rather than take the portacot, which DD doesn't tend to sleep in, we're just going to get a sleeping mat (one of those foam ones) and take her usual sleeping bag and nighttime stuff. We'll probably try and fit in one of the prams (hopefully the big one), and she can also sleep in that if needed. I figure if we have the pram, then we won't need a highchair. I'll put in plenty of toys and familiar stuff too to keep her occupied but I'm figuring that we'll have to be pretty vigilant in watching her so she doesn't wander to far.
As for food, she eats what we eat so that won't be an issue, it will just be taking her milk for the 2/3 nights we're away.

As I said, we haven't done this yet with a toddler, so it will be a big experience! I'm hoping it works, coz with building a house next year, I think camping will be our main holidays for the next few years!