In this paper, we study the behavior of miniaturized high-order waveguide filters, constructed by loading a hollow metallic waveguide with resonant pins, to form a locally-resonant metamaterial. Such composite pin-pipe structure supports a guided-mode with adjustable bandwidth below the resonance frequency of the pins. We show that the position and bandwidth of this sub-wavelength mode are decoupled from the arrangement of resonant inclusions. We experimentally demonstrate the customizability of the bandwidth and the robustness of the passband against geometrical scaling. Our prototypes, which are an order of magnitude smaller and lighter than traditional filters and compatible with standard waveguide ports, may find applications in future satellite systems, for 5G or internet over satellite technologies.