  We report on recent results from a target-of-opportunity program to obtain
spectropolarimetry observations with the Southern African Large Telescope
(SALT) on flaring gamma-ray blazars. SALT spectropolarimetry and
contemporaneous multi-wavelength spectral energy distribution (SED) data are
being modelled self-consistently with a leptonic single-zone model. Such
modeling provides an accurate estimate of the degree of order of the magnetic
field in the emission region and the thermal contributions (from the host
galaxy and the accretion disk) to the SED, thus putting strong constraints on
the physical parameters of the gamma-ray emitting region. For the specific case
of the $\gamma$-ray blazar 4C+01.02, we demonstrate that the combined SED and
spectropolarimetry modeling constrains the mass of the central black hole in
this blazar to $M_{\rm BH} \sim 10^9 \, M_{\odot}$.
