I just did this
I just switched from a Concorde to the Oddessy. I set it in place, using the normal hold-down, and measured for a spacer block in front. I cut a piece of wood to that dimension, and retained it with one screw in from the front channel on the tray so it doesn't walk out. Took 10 minutes, and I have a tray that will work with either battery now.
"The Magic Carpet"
Hobbs 515 in 9 years (would have flown more this year if not for fire smoke)
also LS-6-15/18 sailplane
VAF donation Dec 2017