Touring Equipment

So me and a friend are already thinking about a tour next summer. Something big it'll be his first time abroad (with a bike) and we are debating whether to do it for charity.

It'll probably be based around hostels so we can pack lighter but taking bivi's just in case.

I'm thinking of using a big seat bag, rack (which I can strap bivi+bag to) and probably one of those frame bags.

Do you think that'll be enough storage space for a light weight tour?

Thinking about it I may even strap a light weight tent to the rack too. Like the £30 flood victim jobbie Ed has.

Jobst would call that overkill.
Here's his equipment for an 18 day jaunt through the Alps: