Nuclear fusion could offer clean, abundant energy. However, managing the power exhausted from the core fusion plasma towards the reactor wall remains a major challenge, compounded in emerging compact reactor designs promising more cost-effective pathways towards commercial fusion energy. Alternative Divertor Configurations (ADCs) are a potential solution. In this work, ADC exhaust control is demonstrated for the first time, employing a novel method to diagnose the neutral gas buffer which shields the target. Our work on MAST-U shows that ADCs tackle key risks and uncertainties for fusion energy: 1) their highly reduced sensitivity to perturbations enables active exhaust control in otherwise unfeasible situations and facilitates 2) passive absorption of transients which would otherwise damage the divertor; furthermore, 3) isolating each divertor from other reactor regions enables near-independent control of the divertors and core plasma. Our work showcases the real-world benefits of ADCs for effective heat load management in reactors.