  We compute the field-angle-resolved specific heat and thermal conductivity
using realistic model band structure for the heavy-fermion superconductor
CeCoIn5 to identify the gap structure and location of nodes. We use a two-band
tight-binding parametrization of the band dispersion as input for the
self-consistent calculations in the quasiclassical formulation of the
superconductivity. Systematic analysis shows that modest in-plane anisotropy in
the density of states and Fermi velocity in tetragonal crystals significantly
affects the fourfold oscillations in thermal quantities, when the magnetic
field is rotated in the basal plane. The Fermi surface anisotropy substantially
shifts the location of the lines in the H-T plane, where the oscillations
change sign compared to quasicylindrical model calculations. In particular, at
high fields, the anisotropy and sign reversal are found even for isotropic
gaps. Our findings imply that a simultaneous analysis of the specific heat and
thermal conductivity, with an emphasis on the low energy sector, is needed to
restrict potential pairing scenarios in multiband superconductors. We discuss
the impact of our results on recent measurements of the Ce-115 family, namely
CeTIn5 with T=Co,Rh,Ir.
