I'm unconvinced of the need to backup sd cards when traveling. Maybe transfer them to a medium that's cheaper $/Gb if you shoot a lot, but it also sounds like you are bringing tons of sd storage.
Aside from crushing them you'd be hard pressed to lose your data, especially with newly purchased cards.
Generally, photography is a very gentle use of digital storage as you write pretty infrequently. Use an sd card as a cache drive or virtual ram and you'll destroy it fast. If you fill and empty a card daily, you'll still get years of service out of it.
I say relax about backup, digital mediums are far less fragile than film which is super easy to wreck. Make sure you have enough capacity, and buy a small Pelican case to put the full ones in.
Then you can drive over them with the vehicle!