I did this today. It was my long endurance day and I had to cut it short after 4 miles (inner leg rash). I was looking to do something more and I though of the challenge.
Used 2x25, for 64; just over 10 min.
I burned myself out way to early. Tried for 24x20x20.. Ended up getting something like 24x10x5x5x5x3x............
Slow and steady wins the race I guess.
No bumper plates, and forgot all about them after about the 12th rep.