I just pack my empty panniers and gear into a single large duffel. Sometimes I take the duffel as my carry-on item and sometimes I check it usually depending on airline policy for international flights. I always use my handlebar bag with all the valuable as my personal cabin item. During my tour, I roll the duffel up with a couple of shirts and a pair of long pants inside. The rolling helps reduce wrinkling. Then I strap the duffel on top of the rack.

That said, I've never taken camping gear on an international tour. On domestic tours when I have taken camping gear, I pack the bulkier but lighter items as well as any pointy things into the box with the bike and usually FedEx that to my destination.