Recent advances such as multigrid and deflation have significantly accelerated Dirac operator solvers in lattice QCD. However, the substantial setup costs of these methods have impeded their application in the repeated Dirac inversions required for Hybrid Monte Carlo (HMC) ensemble generation. Building on earlier work in the RBC/UKQCD collaboration, which showed that renormalization-group (RG) blocked coarse lattices with $a^{-1} = 1$ GeV provide a good approximation of the low-mode structure of Mobius domain wall fermion (MDWF) Dirac operators on $a^{-1} = 2$ GeV lattices, we investigate how to exploit this correspondence in practice. Specifically, we study how filters and 5th-dimensional tuning on the coarse lattice can be used to control the influence of high modes in the coarse-fine mapping. Because RG blocking is computationally inexpensive, this approach may offer a way to incorporate multigrid-style acceleration directly into ensemble generation.