Bill decided that maybe...all controls could be put on the left handlebar—clutch, gas and brake?
You can see from this pic of the right handlebar that that he has run a cable to it from the left:
It was a pretty gear-heavy group of riders with nice bikes set up for off-road (not everyone was wearing their gear yet in this photo for the ride to come).
The water crossing was fairly tricky and swervy, bringing down a rider or two or causing them to veer off into the bushes. But Geoff was right, Bill with his one arm can shred.