Ascent

Tough to get right, but rewards persistence and experimentation. Thanks to @nGord for the particularly helpful hint. For those who want a broader hint:

Spoiler

Pay attention to the R walking properties involved in different stacking configurations -- different R styles on different R styles. Takes some experimentation.

Another R property used multiple times on this level is, of course,

Spoiler

R bots freezing and unfreezing. Pay attention to the effect some (yes, more than one!) of the draggables have on this.

And, yes, some timing.

I did a video solution that I'm reasonably confident is the intended solution, based on the comments above. Doing the video really required me to nail down a few tricky timing issues.

Spoiler: Video Solution

Spoiler: VS (v1.6.2)