Cassie Scallon attempted the FKT on 3/09/2019, but came up a bit short:
"I just wanted to follow up on the unsupported FKT attempt I had on the Joshua Tree Traverse last weekend. I missed Sarah Keys' time and ended up coming in 5:36:12, which looks like it may be the 2nd fastest time reported to your site. I uploaded my run on Strava here ."
Today, Apr 12, 2019, I will attempt another unsupported Joshua Tree double traverse (a.k.a out-and-back or yo-yo) with the goal to beat Jason Hardrath's impressive time from Dec 2018. More info at http://www.christofteuscher.com/aagaa/announcement-another-joshua-tree-double-traverse-attempt.
I plan to start around 5pm.