Hi, I made some markings on page 8 (and I attached page 8 below too) but I'll also explain what I would do just in case.
For the first line, the LH and RH are mostly just alternating in those two-note groups (stem down = LH, stem up = RH). For most of them I would do 2-3, 1-3, or 1-2 (RH) or 3-2, 3-1, or 2-1 (LH).
For the second, third, and the first half of the fourth line, take the RH top melody notes with your pinky. The three notes that come before the quarter notes can likely all be done with 1-2-3 or 1-2-4. For the left hand, it'll also mostly just be 5-3-2-1 or 5-4-2-1. If there's a whole note on the bottom like in the first beat of each measure, just take it with your pinky and then cross your hand over.
The end of the fourth line and the beginning of the fifth line are pretty simple. The RH takes the top notes with 5-3 or 5-2 and then the thumb takes the bottom note. The LH holds the low E with the pinky and takes the top notes with 2-1 or something similar.
I put "simile" in a few spots to indicate that the fingering pattern continues throughout the measure. Let me know if something isn't clear.
Also - Rousseau posted a video of this piece with the MIDI visualizer. Maybe if you slow down the speed and watch his fingers you can get a better idea of how the cadenza is played.
at 3:10