Is there record of a bosonic Stern-Gerlach measurement?

You can absolutely do a corresponding experiment with light. In fact, it's the easiest way by far. Instead of a magnetic field, you would use a polarizing beam splitter to separate the two states, which as the name suggests is a cube that reflects light of one polarization and passes light of the other polarization. To do a Stern-Gerlach like experiment all one needs is a polarized photon source, a few of these cubes and a few half waveplates to change photon polarization, and then some photon detector looking at outputs.

This wouldn't normally be called a Stern-Gerlach experiment, which is specific to using a magnetic field to separate particles with magnetic moments, but the mathematics describing it is the same, as is the basic lesson that angular momentum is quantized and measurements in different directions don't commute.

As for atoms, a quick search found a Stern-Gerlach like experiment with not just single atoms, but a BEC: http://www.uibk.ac.at/exphys/ultracold/projects/rubidium/rb87bec/ I can't immediately find a single-atom experiment with Rubidium, but I bet it's out there if you look around.