Wanted to say thanks to all for the advice.

#1 - I'm looking into the Mosquito Flats to Mono, but haven't done it yet. Had the opportunity to do a back country hike I've been long looking forward too which was: (see #2)

#2 - Did Aspendell (Lake Sabrina) to Hungry Packer Lake for an over nighter. (Beautiful, great fishing, and my #1 fave place in the Sierra Nevadas so far). Peaked at just a touch over 11,000 feet. No major issues. Just a tiny barely fuzzy headache while sleeping. I drank more water and popped some aspirin and it vanished.

#3 - I have added Nuun to my pack and on my first trial, to the hike above, I took about 2-3 complete tablets. I'm not sure if it helped, but I didn't have any side effects that I was aware of (and that was my primary test).

#4 - I have a local hike this week here at home in the L.A. area, and then the following week I'm doing the exact same Hungry Packer Lake hike. Then Whitney starting Sept 2nd.

So, again, thanks for the pointers!