There's nothing particularly wrong with those kit lenses, the main negatives being that they are fairly slow. The 12-50 is weather resistant.
Now, what to recommend would depend on what walk/tramp/hike you are intending on doing. I'd suggest that the longer lens will be rarely, if ever used (so pack it just in case, but no need to rent a better one). Were it me, I'd take/get one or two primes. Going ultra light, the Olympus 17mm or Panasonic 20mm would serve for most situations. Add in the Olympus f1.8 45mm for something a bit longer. If you want a little wider, either stitch, or consider the tiny f2.5 28mm Panasonic. Three of them would take up about as much room and weight as a zoom.
Your other option is to take the 5D with a decent 35mm or 50mm prime, or even the 40mm pancake.
Whichever option you take, a monopod, which can double as a walking stick, would be very useful.
I'd hesitate to take something unfamiliar on a trip.