It's been a while since I've been on the CF forums, but I know a number of people reported being less sore from doing a marathon after they started crossfit compared to when they were doing more distance without crossfit. Endurance work also tends to be fairly specific so there might not be a big carryover between running and rowing with hiking with a pack and ice climbing. Strength will also be more important for what you're doing than in something like a marathon.
As far as strength goes, you might want to give Starting Strength a try although you might be better off with only 2 days a week. When I was doing more endurance work I had better success with somewhat higher reps (maybe 5-10) and less sets than the other way around.
You can also try doing 30-60 minutes of endurance work immediately following a metcon.
You might want to check out the Gym Jones site. They do a lot of crossfit type stuff mixed with endurance mountain sports.