For me, 30D + 12-24 without a seconds thought.
Altitude is a real female dog if you are not used to it, but the difference in camera weight wont make any difference unless you are trying to sprint up to 8000m. Dehydration is one of the biggest problems, so you will have to carry several liters of water, by the time you are packed with all necessities (water + clothing), the difference in weight is meaningless.
My advice is to get fit (but this means CV, muscles will only drag you down and burn oxygen, if you are a gym rat then stop weight lifting). Try and get some acclimatisation trips in. For starters, a few weeks before get a cheap flight to lyon/annecy/geneva and get your self to Chamonix, up the Aiguille de midi and spend a night or 2 at the cabane cosmiques and do some light CV work. When you arrive in Nepal see if you can get a head start on some high altitude trekking
I wouldn't want 18mm FF equivalent in the Himalayas for starters.
If I was doing such a trip I would upgrade to FF immediately and/or buy a small point and shoot. You will only notice the weight saving when going down to a 200g lumix type thing.