I have decided to go in from South Lake- take the trails all the way to Simpson Meadow, 2-3 days or so going down and back to Tehipite and unless running out of time, return up Palisade Creek to Palisade Lake and follow the High Route back to Dusy Basin
That's what I would do, and what I did in 1977, during a similar spell of drought years. Back then there was a sturdy bridge across Palisade Creek at the JMT/Simpson Meadow junction. That bridge is gone now; you have to ford the creek at a wide spot below the old bridge. That spot is well marked. Also, back in the day, there was a log-bridge crossing at Simpson Meadow, but it was badly beaten up then and no longer exists, to the best of my knowledge. Bottom line: a June hike down there this year from the JMT will involve two high-water crossings. I'd probably opt for early August.
The section of trail from the Simpson Meadow/JMT junction to where it intersects Cartridge Creek is absolutely beautiful and is highly recommended. At Simpson Meadow, once across the river, the trail down to Tehipite (at least back in 1977) was in OK shape and easy to follow. It is a hot hike, so be sure to do it early in the day. I saw a few rattlesnakes and some exotic flowering succulents. Open views are hard to find in Tehipite Valley. It has a mixed forest floor, which blocks good views. Bugs were bad down there; I found sanctuary by walking into the middle of the river, to a little rock/sand bar, which was surprisingly free of insects. Great views of the dramatic canyons on the south side of the valley can be had by walking upslope on the north side. I only stayed one night and found the place a little inhospitable because of the insects, the lack of open vistas, and the heat. It is worth a visit for sure. My brother loves this place and has spent weeks there; it is one of his favorites. Go figure.