  We consider itinerant spinless fermions as moving defects in a dilute
two-dimensional frustrated Ising system where they occupy site vacancies.
Fermions interact via local spin fluctuations and we analyze coupled
self-consistent mean-field equations of the Green functions after expressing
the spin and fermion operators in terms of Grassmann variables. The specific
heat and effective mass are analyzed with the solutions satisfying the symmetry
imposed by the coupling layout. At low temperature, we find that these
solutions induce stripes along the lines of couplings with the same sign, and
that a low fermion density yields a small effective mass.
