I did a solo overnight hike starting at Whitney Portal at 5:15 am on July 30th. I got to Trailcamp by 9:00 am, which was much earlier than anticipated. It's hard to gauge how in shape you are based on talking with different people! I then decided I didn't want to stay at the featureless camp for the whole day and headed to the summit.
I left there at 10:00 am. I got to the top at 1:15 pm with picture-perfect weather. After about 30 minutes the nice puffy clouds on top of Mt. Whitney quickly changed to darker ones, so I decided to start heading back. By the time I was at Trailcrest, I could hear thundering.
By the time I made to Trail camp (4:00 pm), I could see the whole ridge was getting hit by what looked like sheets of precipitation. From 12,000ft, I wasn't sure if it was hitting the ground though. Nonetheless, the lighting was pretty scary and definitely got me back to Trailcamp faster. The lesson there is: try to summit before noon this time of the year.
By the way, a great spot to get clean water is at the switchbacks between Trailcamp and Traicrest. It's a good filling time as you are coming back of the mountain and the water is not stagnant like the one by Trailcamp. I then debated getting back to Portal, but ultimately decided to spend the night at Trailcamp.
I left there at 5:00am, and leisurely came down, taking pictures. I was back to Portal before 8:30 am.
On the microspike need, I brought and used them at two locations - one small patch before Trailcamp, and the other sketchier patch right below Trailcrest. Can you do without them? Absolutely. Also, on water shoes, I regret bringing them. The only spot you need to take your boots off is right below Outpost camp. The flooded trail is not gravelly and one could easily walk barefooted - save some weight.
