This record hosts the preprint “Boundary-Condition Quantum Mechanics IV_b” (BCQM IV_b), a companion paper to BCQM IV in the Boundary-Condition Quantum Mechanics series. The BCQM programme develops a discrete, event-based extension of quantum mechanics with a finite coherence horizon W_coh, from which spacetime structure, inertial response, and an intrinsic inertial-noise floor are intended to emerge. BCQM IV_b focuses on the numerical side of this programme. It develops and tests a minimal inertial-noise pipeline built from a simple, W_coh-blind control kernel (“bcqm_toy_3”) defined at the level of a single event thread. The paper describes how acceleration time series are generated, how one-sided power spectra are estimated, and how a noise amplitude A and characteristic frequency omega_c are extracted and fit to log–log scaling laws. A first set of results demonstrates that, for a deliberately W_coh-independent kernel, the fitted exponent β in the scaling law A(W_coh) ∝ W_coh^{−β} is statistically compatible with zero, as required for a clean control model. The paper then extends the analysis to simple configuration-space cluster toys. An independent-probe cluster model (“bcqm_cluster_toy”) is used to study how the centre-of-mass (COM) inertial-noise amplitude scales with the number of probes N. The measured behaviour A_COM(N) ∝ N^{−1/2} and an almost N-independent spectral centroid confirm the expected COM suppression for independent probes and provide a baseline against which more realistic, correlated cluster kernels can be compared in future work. The dimensionless results are finally mapped into SI units for representative mechanical and atomic benchmark platforms, yielding order-of-magnitude estimates for the BCQM inertial-noise floor and associated thermal crossover temperatures. Taken together, these results provide a numerically validated control model, a documented pipeline from event-level dynamics to inertial-noise spectra, and simple few-body benchmarks that will be used in the gravitational and emergent-curvature analysis developed in BCQM V. The companion simulation and analysis code for this paper is archived separately on Zenodo under DOI 10.5281/zenodo.17815304 and is referenced in the text.