When we head to our place in Northern Ontario for holidays each year, I carry both the 4x5 and the 8x10 (I'm driving though , so it's easier). For film, I take unexposed 4x5 in the store packages which is easy. The problem is AFTER it's exposed - how do you carry it until its gets developed and STILL be able to use your film holders? This is also easy ... I made black ABS tubes with one threaded end and a thread cap to seal them light-tight (and also very liquid-tight within reason). As I unload my holders, I always unload them into the tube in order of my photo log and when I get home, I develop them from the tubes in reverse order so that they don't get mixed up. Because I cut my own 8x10 from rolls of Plus-X Aero, I have two tubes for the 8x10, one for unexposed sheets and one for the exposed sheets. This way I can take as many photos as I want without having to worry about the development until I get home. Also, the tubes are VERY rugged and if something happens physically to the truck we take, the film will likely survive and if it doesn't, we likely didn't either ....
cheers