Get a 60D crop camera for one... Not as weathersealed as the 7D, but weather resistant nonetheless (which is nice). More importantly, it has a "decent plastic" body rather than an alloy one. In cold weather, metal is freezing to the touch. You might want to stay away from it.
For a lens, there's not much weathersealed for the wide end of the zoom for crop cameras. Also, there are few if any lenses that cover all the range in one lens, without significantly sacrificing image quality. Also, weathersealed lenses usually have a metal build.
You'll have to compromise something. Either you get the whole range in one lens and image quality is somewhat compromised; or you get better image quality but you take two lenses instead of one, or you skip out on some of the range. And if you want the best image quality, you're probably taking a metal lens (which although usually weather resistant, will be cold in subzero temperatures).
The Canon EF-S 15-85 f/3.5-5.6 IS is a nice wide range crop lens. Not weathersealed, not heavy, decent wide end, very good image quality throughout its range (and it has IS). But it won't do real tele shots. You could take a second lens for that, or skip on it.
The Canon EF 70-300 (L) IS would make a nice addition for tele range. The non-L is lighter, plastic and a "step down" on pretty much every aspect - sharpness, contrast, focus speed, build quality, price... Still decent enough image quality on a crop camera though. The L version is incredibly sharp with good contrast. It's heavier, pricier and metal. It will work nicely with a weathersealed body though (but you'd still lack weathersealing on the wide zoom lens).
The Canon EF-S 18-200 f/3.5-5.6 IS is a lens that covers a nice wide range with IS. Image quality is ok, but not as good as the other lenses I mentioned. Only take this if you are willing to compromise on image quality, and can really only take one lens.
I'm not very up to date with superzooms. Generally I'm very sceptical of their IQ, especially from other manufacturers. It's always some sort of compromise.
Concerning the 24-105L, I'd stay away from it if you're taking a crop camera. You can't get wide shots with that on a crop camera without taking another lens, and then you'd have two lenses while still not having any far tele range zoom.