Regional monitoring networks are crucial for environmental assessment in South Africa, particularly for glacial studies. However, their cost-effectiveness remains a subject of debate. A randomized field trial was conducted across South Africa to assess the performance of different monitoring configurations. Data were collected using an environmental quality index (EQI) model, with robust standard errors accounting for measurement uncertainty. The EQI revealed that a specific monitoring configuration reduced costs by 15% without compromising data accuracy compared to existing networks. This randomized field trial demonstrated the potential of optimising regional monitoring networks for cost-efficiency in South African environments, particularly for glacial studies. Future research should validate these findings with a larger sample size and integrate predictive analytics into monitoring strategies. Regional Monitoring Networks, Cost-Efficiency Assessment, Randomized Field Trial, Environmental Quality Index (EQI), Robust Standard Errors The empirical specification follows $Y=\beta_0+\beta^\top X+\varepsilon$, and inference is reported with uncertainty-aware statistical criteria.