It wasn't too bad the first couple times through 21 Rd, I took the bypass around the overhang the first time, then stayed in the creek bed the 2nd time, but the third time it was washed out really bad and i ended up on the cable just to get through one section. It was about the same width as a k5, actually about 1/8" narrower according to my paint. Shortly after that I pulled the steering box off the frame. Broke one of the mounting ears, broke 2 bolts and pulled one bolt through the frame. ouch! I beefed it some more after that, weld in repair kit in addition to the bolt on brace kit.
I know the spot you're talking about, you can fit a jeep width vehicle pretty easy, but bronco size or a rover is the absolute max, and you better not have more than a 12.50 wide tire on it! Some places I don't even try to go.
Carnage Corner was a lot more fun after the crossover steering conversion. The first time i had to pretty much point straight ahead and go for it, with steering i could go around the rocks instead of over them, it was pretty cool!
As for the 205 twin stick with a Doubler, it won't be a problem, a custom home built shifter would be very possible, it's just how well you carry it off. i ran a pretty ugly twin stick for a couple years that worked really well.
SW-ORD