For your hiking, unless you are in really, really good shape, size and weight will be like a boat anchor. For the rest of your trip, keep it simple and keep it light. Also consider the safety of your gear...it can be an beacon for sticky fingers, especially if you are traveling solo.
The simplest way to go is with just your G15 and lots of cards and extra batteries and a power adapter for charger. If you are traveling with your own "sherpa", then perhaps bring the 5D and 2-3 lenses max, backed-up with your G15.
Thinking outside the box, if this was my trip, I'd go M43 with a couple of wide-range zooms. The IQ is at least as good as your 5D (I'm assuming you have the original 5D) and most likely better. Both Olympus and Panasonic have very good bodies that are small, light weight, and less intimidating to use when photographing people. The lens selection is very adequate and the optics on the premium lenses are superb.
For my last journey across the pond, my Nikon system stayed at home and I went totally with my M43 bodies and lenses. I love the IQ of the Nikon, but schlepping the weight and bulk is becoming less appealing as I get older! My previous trips included both systems and what I found was in urban settings the M43 was liberating in many way.
My normal style tends to favor wide angle lenses and so I tend to shoot a 7-14 and 12-40 supplemented by a 35-100mm. If I really want versatility and take less, I'll leave the 12-40 and 35-100 behind and replace it with a 14-150mm lens and I'm prepared for almost everything. With two bodies, two lenses, a pocket full of batteries (the m43 systems eat batteries at 300-400 frames per charge-less when shooting video) and a few 32GB SD cards, I'm good to go. As a bonus, the smaller cameras and lenses make me appear less threatening and I blend in more like a tourist.
Hope this helps and have a safe and successful journey!