Well, if you're going to be out in rain and mud, do yourself a very big favor and put a UV protector on the lens. I generally don't use them (though I should) but anytime I think the lens may get dirty, the UV protector goes on just to be sure. Worst case you throw away a $20 filter rather than a $500 lens.

Regarding alcohol, yeah, but frankly, I carry very little with me when I go hiking. Less stuff is better. So absolute worst case a bit of water goes a long way or you can just breathe on the lens to get it a bit moist and then wipe off with the microfiber cloth. Or your t-shirt if you don't have one of those.