  PSR J1141$-$6545 is a precessing binary pulsar that has the rare potential to
reveal the two-dimensional structure of a non-recycled pulsar emission cone. It
has undergone $\sim 25 \deg$ of relativistic spin precession in the $\sim18$
years since its discovery. In this paper, we present a detailed Bayesian
analysis of the precessional evolution of the width of the total intensity
profile, to understand the changes to the line-of-sight impact angle ($\beta$)
of the pulsar using four different physically motivated prior distribution
models. Although we cannot statistically differentiate between the models with
confidence, the temporal evolution of the linear and circular polarisations
strongly argue that our line-of-sight crossed the magnetic pole around MJD
54000 and that only two models remain viable. For both these models, it appears
likely that the pulsar will precess out of our line-of-sight in the next $3-5$
years, assuming a simple beam geometry. Marginalising over $\beta$ suggests
that the pulsar is a near-orthogonal rotator and provides the first
polarization-independent estimate of the scale factor ($\mathbb{A}$) that
relates the pulsar beam opening angle ($\rho$) to its rotational period ($P$)
as $\rho = \mathbb{A}P^{-0.5}$ : we find it to be $> 6 \rm~deg~s^{0.5}$ at 1.4
GHz with 99\% confidence. If all pulsars emit from opposite poles of a dipolar
magnetic field with comparable brightness, we might expect to see evidence of
an interpulse arising in PSR J1141$-$6545, unless the emission is patchy.
