Figure I'll chime in with my thoughts as I'll be doing the same trip starting in September, except that I'm traveling on a dual sport motorcycle rather than bicycle. I know, a little different, but I'm planning to take a very similar amount of kit. After some shakedown rides I've got my kit to where I think I'm happy.
Sirui N1204 Tripod
I do a lot of hiking on my trips as well, and although the 15-85 is rather wide, I wouldn't think of leaving behind my 11-16 for the shooting I do. I am still a bit undecided on my 70-200, though. Some trips I've taken it, some I haven't. It seems that when I bring it, I don't use it much, but when I don't have it I regret not bringing it. Maybe I'll start the trip with it and make a decision to keep it or send it home before crossing into Mexico.
So I guess my recommendations would be to take the 10-22 (and it sounds like you really enjoy this lens), either a standard zoom (17-55,15-85, 24-105) or perhaps just a prime in this range, and a telephoto (70-200/4, 70-300, 55-250). I really like my 70-200, but if you took, say, 10-22, 30, and 55-250, you wouldn't even have much for gaps in focal length.
My best recommendation, though, would be to take a couple shakedown rides with some different gear and see what you actually shoot with, and what you wish you had with you.
Keep the rubber side down!
Canon 7D | Opteka 6.5mm/3.5 Fisheye | Tokina 11-16/2.8 | Canon 15-85/3.5-5.6 IS USM | Canon 35/2IS | Canon 50/1.8 II | Helios 44-2 58/2 | Sears 135/2.8 | Canon 70-200/4L
Canon T1i | Canon 18-55/3.5-5.6 IS