Wolf-Rayet (WR) stars are the progenitors of hugely energetic explosions. Although they often occur in binaries, we don't understand the role of companion stars in creating the conditions for particular supernova explosions. Interaction in binaries can affect the WR wind geometry, and possibly provide the rapid rotation thought to be required for GRB production in specific supernovae. Time-dependent spectropolarimetry can help us to better characterize the circumstellar material created by the stars’ colliding winds, and thus probe wind interactions and geometries that diagnose rapid rotation. I present results from new Monte-Carlo radiative transfer models of WR + O binary systems, including both continuum and line polarization effects. Using these models and high-quality data across the orbits of multiple such systems, obtained with RSS at the Southern African Large Telescope, I link colliding wind geometries with spectropolarimetric evidence. I perform an independent test of the models by comparing the simulation results to existing models based on spectroscopic data.