Large, fast cards are cheap. Buy enough for your trip and a few more.
During my last couple of trips to Spain, Serbia, Greece, seven plus weeks on the road between the two trips, I simply used the cards once and then used a pair of Hyperdrives for back-up and an iPad to check the images and serve as a tertiary back-up. The iPad handled the d800 raw files just fine.
For the most part, I use main stream and medium to fast 16 to 32 gb cards.
If I'm just shooting for a few days, I won't even bother with the Hyperdrives and simply work like film days, shoot, change the "film" and then ingest and process the raw files when I get home. It's sort of nice not to have to download and process nightly on the road today so I can relax and socialize when I travel, joist like the good old days.