Scale focusing by feel is one of the most powerful but incomprehensibly under-practiced techniques for rangefinders. But for something like the Rollei 35 (and other scale focus cameras like the Olympus Pen), another approach works really well.
Instead of learning how to estimate how far away your subject is, just learn several common framings and what the corresponding distances are, then extrapolate from there.
For example, let's say you take a lot of photos like these:
1) Full length portrait, vertical orientation
2) 3/4 length portrait, vertical orientation
3) 1/2 length portrait, horizontal orientation
All you have to do is figure out three rough distances for whatever lens you have!