This study showcases a global, heterogeneously coupled total water level system wherein salinity and temperature outputs from a coarse-resolution ($\sim$12 km) ocean general circulation model are used to calculate density-driven terms within a global, high-resolution ($\sim$2.5 km) depth-averaged total water level model. We demonstrate that the inclusion of baroclinic forcing in the barotropic model requires careful treatment of the internal wave drag term in order to maintain the fidelity of tidal results from the purely barotropic model. By accurately capturing the internal tide dissipation within the coupled system, the resulting heterogeneously coupled model has deep-ocean tidal errors of 2.27 cm, outperforming global, depth-resolving ocean models in representing global tides. Moreover, global median root mean square errors as compared to observations of total water levels, 30-day sea levels, and non-tidal residuals improve by 1.86, 2.55, and 0.36 cm respectively. The drastic improvement in model performance highlights the importance of including density-driven effects within global hydrodynamic models and will help to improve the results of both hindcasts and forecasts in modeling extreme and nuisance flooding. With only an 11\% increase in computational time as compared to the fully barotropic total water level model, this efficient approach paves the way for high resolution coastal water level and flood models to be used directly alongside climate models, improving operational forecasting of total water levels.