Definitely best to go have a look at some first. I also have a 5d Mk II. For really lightweight travel I have a Silk Sprint Mini II (
Amazon Link). It's cheap, very small, very light and looks the part too. Will it hold your camera in a storm? No. Is it anywhere near as good as larger alternatives when you have that option? Definitely not. But it is tiny and is better than no tripod at all. I take it with me on all foreign trips (it easily slips into a small rucksack).
I have used it with my 70-200 f4 IS, but I wouldn't go any bigger than that at all.
Cheers,
Steve
ImageArcade; Photography By Steve Ayres