For those who have not done this kind of elevation loss and gain, the downhills are the brutal part. So you need to do a lot of steep elevation training, going downhill especially. The downhills can be absolutely brutal.
If you would like a severe training run a couple weeks before the trip, I am willing to help with logistics on a Desert Skyline Trail training run in Palm Springs. The trail is 11 miles long, with a 8,000' elevation gain. The last 1,000' you may want to skip. But a 7,000' uphill run and then return might be beneficial. The first 3,000 foot gain will be tough and running back down this section might not be a good idea, but just hiking it will be very beneficial after you have ran up 7,000' and then ran down 4,000'.
The trail will probably be hot after 10 AM, so you want to start around 7 AM or earlier. There is no water. When you get to 7,000' gain, you cannot risk going back down without enough water in your pack. And if you are too tired, you best not try to return, safer to hike up the last 1,000' which is the steepest section, and then take the tram down.
I can hike from the top down, and if anyone is having difficulty, I can bring extra water and lead you up to the tram. This section is not well marked in places, so you would want someone who knows the route to assist. Also, there could be snow and ice on this section, you might need to bring microspikes. Should not be any snow at 7,000' gain mark.
If everyone makes it to 7,000' and feels they can make it back down okay, then I will just hike down to the bottom, that way if anyone has difficulties I can help. I am getting too old to do this kind of a run, but hiking it is not too difficult.