Yes. The usual rangefinder technique in portrait orientation is to rotate the camera so the shutter release stays at the top, keep your right index finger on the shutter, and move your left hand off the lens to support the lower opposite corner of the camera body instead.

If you need to change aperture on a lens ring, make the adjustment first, then return your left hand to that corner support position so it doesn’t block the finder window.

In practice, this is simply one of the ergonomic compromises of rangefinder-style cameras: portrait shooting with the optical finder is often a bit awkward compared with an SLR or EVF-based approach. So you’re not missing a secret trick — the standard solution is to support the body rather than the lens when shooting vertically with the optical finder.