Dynamic light scattering (DLS) and small-angle neutron scattering (SANS) were used to characterize the microstructure of a reverse micelle system consisting of ethanol, water, and surfactant n-hexadecanes as an analytical framework to understand the structure and stability of a model platform for biofuel formulations. Best-fit modeling of SANS scattering data suggested that the micelles are better described as ellipsoids rather than spheres, with the (geometric) diameters of stable micelles increasing from 2.4 to 7.5 nm as a function of the increasing water content as well as surfactant concentration. Fitted diameters from DLS measurements followed similar trends, but DLS measurements overestimated the interior of the micelles by roughly 2-3 nm because DLS measurements are based on the full hydrodynamic radius, including the surfactant shell. SANS only detects the nanopool interior, a significant advantage. The choice of Surfactant altered the stability at temperatures below 10 degrees C, but the micelles readily reassembled when the temperature was raised toward room temperature. This model framework was then used to quantitatively assess "real world" surrogate fuel system consisting of ethanol, commercial ultra-low sulfur diesel, and a surfactant derived from minimally processed corn oil waste. These surrogate mixtures were probed over temperatures ranging from 10 to 60 degrees C, at concentrations up to 740 mM, and at various-saturation levels with results similar to the model system. Results confirmed that this analytical framework can be used to understand optimization of biofuel formulations to meet industry standards for stability, cold-flow, and other performance requirements.