  A $\widetilde{\chi}^2$ analysis of standard model accretion disk synthetic
spectrum fits to combined $FUSE$ and STIS spectra of V3885 Sagittarius, on an
absolute flux basis, selects a model that accurately represents the observed
SED. Calculation of the synthetic spectrum requires the following system
parameters. The cataclysmic variable secondary star period-mass relation
calibrated by Knigge in 2007 sets the secondary component mass. A mean white
dwarf (WD) mass from the same study, that is consistent with an
observationally-determined mass ratio, sets the adopted WD mass of
$0.7M_{\odot}$, and the WD radius follows from standard theoretical models. The
adopted inclination, $i=65{\arcdeg}$, is a literature consensus, and is
subsequently supported by $\widetilde{\chi}^2$ analysis. The mass transfer rate
is the remaining parameter to set the accretion disk $T_{\rm eff}$ profile, and
the $Hipparcos$ parallax constrains that parameter to
$\dot{M}=5.0{\pm}2.0{\times}10^{-9} M_{\odot} {\rm yr}^{-1}$ by a comparison
with observed spectra. The fit to the observed spectra adopts the contribution
of a $57,000{\pm}5000$K WD. The model thus provides realistic constraints on
$\dot{M}$ and $T_{\rm eff}$ for a large $\dot{M}$ system above the period gap.
