Can you line under the bed with contact so you don't need bags? Unless you are doing Gibb River Rd or other red dirt road, then you could pop them into garbage bags for that stint of the trip.

Rivlas's point of using the vacuum bas but not vacuuming them is a good idea too.

Where you headed? We did 12 months around Aus in a camper trailer for our honey moon, and we plan to do it again in a few years with the kids. I'm jealous!