Mumbles, I think don't fall in is good advice. Let me explain.
I do alot of my fishing solo and on foot, and every time I am wading in potentially dangerous water falling in is one of my top risks. It is very easy to get a foot entrapped in between rocks and quickly be in a very bad situation. As fall is approaching and its getting colder it becomes even more of a risk.
Although I have only been flyfishing a for a few years, I have yet to fall in with waders on
I have fished the upper yak/cle elum on foot before and I remember some hairy wading. I didn't find any fish either, so I hesitate to claim what flies will work well. Hopefully the october caddis will be active for you!