All simulations are an abstraction over real physics. Some are more and some less detailed. Even Systems ToolKit, the most widely used commercial six Degrees-of-freedom software package, is an abstraction. To properly model processes taking place during various phases of spaceflight, one needs for instance understand that a rocket is not a solid cylinder: it has propellants that slosh in the tanks, it bends and vibrates etc. etc. At re-entry, heat and aerodynamic loads interact with each other in highly complicated ways.
Using Kerbal Space Program, STK, Orbiter, GMAT or whatnot in answering the question, one has to fully comprehend their limitations and error margins, and the underlying physics. Is the resulting answer sensitive to the degree of fidelity? Do the numbers you get in various simulators essentially match each other (e.g. time-to-MECO or estimated lifetime-in-orbit...)?
In short, simply citing KSP as an authoritative reference won't do. Real engineering considerations should be included into the answer, based on own experience, books, technical reports, or articles. Simulations can make an excellent tool to get visualizations for the answer (diagrams, graphs, orbit tracks), however.