The MARE experiment is designed to measure the mass of the neutrino with sub-eV sensitivity by measuring the beta decay of 187Re with cryogenic microcalorimeters. A preliminary analysis shows that, to achieve the necessary statistics, between 10,000 and 50,000 detectors are likely necessary. We have fabricated and characterized Iridium transition edge sensors with high reproducibility and uniformity for such a large scale experiment. We have also started a full scale simulation of the experimental setup for MARE, including thermalization in the absorber, detector response, and optimum filter analysis, to understand the issues related to reaching a sub-eV sensitivity and to optimize the design of the MARE experiment. We present our characterization of the Ir devices, including reproducibility, uniformity, and sensitivity, and we discuss the implementation and capabilities of our full scale simulation.