Galactic interstellar emission contributes substantially to Fermi-LAT observations in the Galactic plane, where the majority of Supernova Remnants (SNRs) are located. We have developed a method to explore some systematic effects on the SNRs regions caused by interstellar emission modeling. We created eight alternative Galactic interstellar models by varying a few input parameters to GALPROP, namely the height of the cosmic ray propagation halo, cosmic ray source distribution in the Galaxy, and atomic hydrogen spin temperature. We have applied it to eight representative SNRs chosen to encompass a range of Galactic locations, extensions, and spectral properties. The models were fitted to the LAT data with free independent normalization coefficients for the various components of the model along the line of sight in each region of interest. We will discuss the results and compare them with those obtained with the official LAT interstellar emission model.