Space radiation is harmful to electronic devices, leading to transient and permanent faults in the on-board systems of a satellite. In traditional satellites, radiation-hardened (rad-hard) devices are employed to mitigate the radiation effects on the electronics. However, in Cubesat based missions, a solution based entirely on rad-hard components is not always feasible due to its high costs, and the limited availability of this type of devices. Therefore, in low-budget small satellite missions, alternative development approaches are needed to mitigate the radiation effects on their systems. One such approach is the combination of rad-hard devices and commercial-off-the-shelf (COTS) components in order to create a cost-effective, fault-tolerant system for use in the satellite's subsystems and payloads. This paper describes the design of a processing module for Cubesats, employing a rad-hard SoC FPGA device combined with COTS components. Additionally, it outlines strategies for the mitigation of radiation effects, resulting in a new fault-tolerant computing platform for CubeSat missions. The work shares decisions, considerations, and studies made during the ongoing project. Furthermore, the research and development activities are conducted in the context of a cooperation between Spacelab at the Federal University of Santa Catarina (UFSC), Brazil and the European Space Agency (ESA), The Netherlands. The anticipated outcome is the expansion of possibilities for CubeSat missions allowing, for instance, deep-space missions. Initially, the proposed processing system is expected to be used as the on-board computer of an endured version of the FloripaSat platform.