Maybe you can pass the oil through a sub-micron filter like a frantz TP style filter. Though I found that did not remove all the black soot. Or maybe use a centrifuge?
personally I wouldnt put WMO or veggie oil anywhere near a common rail. Or even biodiesel for that matter. They have really tight tolerances to get the pressures so high. and the electronic injectors are already less reliable than the mechanicals. Differences in viscosity, acidity, BTU and soot content make this a really bad idea.
If you want to run non-standard fuels get a 12v as a second truck. Thats why I keep mine. Ive run veggie oil and bio through that with no issues at all. If there was ever an engine suited to a zombie apocalypse, its a 12v cummins.