  This paper is one in a series reporting results from small telescope
observations of variable young stars. Here, we study the repeating outbursts of
three likely Be stars based on long-term optical, near-infrared, and
mid-infrared photometry for all three objects, along with follow-up spectra for
two of the three. The sources are characterised as rare, truly regularly
outbursting Be stars. We interpret the photometric data within a framework for
modelling light curve morphology, and find that the models correctly predict
the burst shapes, including their larger amplitudes and later peaks towards
longer wavelengths. We are thus able to infer the start and end times of mass
loading into the circumstellar disks of these stars. The disk sizes are
typically 3-6 times the areas of the central star. The disk temperatures are
~40%, and the disk luminosities are ~10% of those of the central Be star,
respectively. The available spectroscopy is consistent with inside-out
evolution of the disk. Higher excitation lines have larger velocity widths in
their double-horned shaped emission profiles. Our observations and analysis
support the decretion disk model for outbursting Be stars.
