It is proposed that line-of-sight gravity measurements derived from spacecraft-tracking data can be used for quantitative subsurface density modeling by suitable orbit simulation procedures. Such an approach avoids complex dynamic reductions and is analogous to the modeling of convention surface gravity data. This procedure utilizes the vector calculations of a given gravity model in a simplified trajectory integration program that simulates the line-of-sight gravity. Solutions from an orbit simulation inversion and a dynamic inversion on Doppler observables compare well (within 1% in mass and size). and the error sources in the simulation approximation are shown to be quite small. An application of this tecnique is made to lunar crater gravity anomalies by simulating the complete Bourguer correction to several large young craters. It is shown that the craters all have negative Bouguer anomalies.