This paper presents a mathematical tool for stochastic filter design based on reach sets for general Uncertain Max-Plus Linear (uMPL) systems. The reach sets are defined as the computation of the set of all states that can be reached from a known previous state vector (forward) and from an available source of measurement (backward). The existing approaches in [13,10] have exponential complexity, which is an important drawback in higher-dimensional systems. In this work, we propose a max-plus polyhedra-based procedure with complexity that is in practice polynomially-bounded.