  Theories of modified gravity attempt to reconcile physics at the largest and
the smallest scales by explaining the accelerated expansion of our universe
without introducing the cosmological constant. One class of such theories,
known as Galileon theories, predict lensing potentials of spherically symmetric
bodies, such as dark matter halos, to receive a feature-like modification at
the 5% level. With the advent of next-generation photometric surveys, such
modifications can serve as novel probes of modified gravity. Assuming an
LSST-like fiducial dataset, we produce halo-shear power spectra for LCDM and
Galileon scenarios, and perform a Fisher analysis including cosmological,
nuisance, and Galileon parameters to study the detectability of the
aforementioned modifications. With the LCDM scenario as our null hypothesis, we
conclude that it is possible to detect the Galileon modifications at up to
4-{\sigma} if present, or strongly exclude the model in a non-detection, with a
tomography of four redshift bins and four mass bins, an LSST-like set of survey
parameters, and Planck priors on cosmological parameters.
