Mike,
I think I know what you were/are trying to do with the whitewash (rough application, with concentrations remaining on horizontal surfaces), and I think adding a bit more to the sides, with downward streaking will get you there.
BTW, I recognize your callsign from the Battlefront Combat Mission board (my handle there is/was jgdpzr). You still active over there? I don't get over there much anymore because I've been in more of a modeling mode than wargaming mode lately (been in need of a computer update the past year, just now getting to where that is feasible). Miss the place, though. I need to stick my toes back in and see what Steve and Charles are up to these days.