If you're into MYOG, you could put together something from heat-sealable nylon. I have considered doing something similar, and there was a post about this here somewhere.
For most backcountry fishing, I don't take waders. Most of the streams I fish in the backcountry are small enough to be fished easily from shore, or, at worst, by rock-hopping or wet-wading to get to where you need to be. The key for me is the temperature of the water. Some mountain streams are so cold even in mid to late summer that wet-wading isn't a good option. If the water is reasonably warm, though, I'd save the weight and not bring waders.
The 5 or 7 piece stowaway fly rods from Cabela's are actually pretty good--especially for the price. I have an 8'6" 4-wt that I use for most of my fishing on small streams, even when I'm not packing in a distance. It's very light.