Believe it or not these two screen shots are different... top one represents the CG (pink circle) with empty fuel tank, and the bottom one with full fuel tank, Note small change in % Ft:Rr.
Its only an estimate of course based on giving the major components "reasonable" weights (e.g. it assumes the engine is 95kg's as per the minimum in the rules... the driver is 80kg's (my weight!), etc) and then making up to 600kgs (I've assumed the car would have 20kg's of moveable ballast and not included it in the model at the moment) by altering the density of the body... not ideal, but without going into structural calculations to determine required tub thicknesses etc its the best I can do in my spare time!
Oh, and going back to the wheelbase; this is with a driver of my height; 6ft 2", -a bit tall for a typical F1 driver and could represent one reason how the real 2010 cars get smaller wheelbases (maybe... we'll have to wait and see!)...