Wow, THOSE are some symptoms! The diarrhea might indicate something else was at work -- a little food poisoning maybe? That could certainly aggravate AMS symptoms. How long did it take for that to resolve?
Now, get yourself a prescription for Diamox (acetazolamide) Start taking it 24 hours before you go to Horseshoe Meadows.
As for water consumption: You should be able to pee every several hours, and it should be more clear than yellow. More and you're probably drinking too much. Less means drink more.
Electrolyte tablets: I discovered Nuun for my last hike. They settled my stomach every time.
Maybe the night before the demolition derby, drive up to the end of the road at Rock Creek and sleep in or by your car. It's also at 10,000'
Another thing: Try hiking to Mono Pass from the end of the Rock Creek road. That will put you at the 12k elevation of the White Mountain gate. Hang out there several hours. See if you get similar symptoms.
