I drove all over Alaska a couple of summers ago; my #1 recommendation for photographers is to take a headnet, thin gloves and insect repellant.
As for photo backup, if you're in an RV, you should have regular 110 outlets. If not, buy a converter for the 12-volt plug-in so not only can you keep everything charged, but you also don't have to buy battery-powered backup drives. If I were you, I'd buy a couple of inexpensive hard drives (they are now very small and reliable) that you would keep in the RV with your laptop, and run off the 110, plus four-six gigs in memory cards, or however much you'd need for a day's shooting. Four gigs would get you, what, about 200 shots? You could cull on the run, to some extent, so practically, you'd have more than that...
I have the Epson P2000 which would be very handy if you were planning multi-day hiking trips away from the RV, but otherwise might be overkill. It has a nice screen, and all, but all you can really do is store your photos, confirm that they're there, and then download them...At current prices, I'd rather have a pocket full of CD cards...
You'll be surprised, when you get to Alaska, at the relative lack of roads, given the size of the state. You can drive the full length of practically every highway in the state over the course of a week; which is not something you could do in, say, Iowa. You'll also be surprised by the cost of gas, especially in an RV...
JC