I have been a backpacker for a long time and I've done it with Paleo style diets and high carb diets as well. I have a military style backpack that I fill with 60 - 75 lbs. and go very fast for 5 - 6 miles on a daily basis. I once did 12 - 15 mile walks when I had more time.
Anyway, I have found little difference in performance between high carb and low carb/Paleo. In hot weather, low carb/Paleo tends to make me much more thirsty. I understand you will be climbing some steep hills, but unless you are literally running up the hills, extra glycogen is not an issue. High fat snacks like nuts and seeds, eaten the night before and during the event, will keep your fuel steady. I have found that I can actually go further eating Paleo style without "hitting the wall". When I eat high carb/low fat, there will come a point where I crash and burn.....this never happens eating high fat Paleo.
That said, the only real disadvantage I have found with high fat Paleo is that it doesn't seem to work well in high temperatures. I tend to need much more water and tire more easily as a result. This is probably due to the low water content in many of the foods I was eating and I have never been one to drink much water. I don't think you will have a problem if you drink plenty of water.