I was thinking about installing a drain but after search though the old reliable Grainger, McMaster-Carr, MSC Direct and other online catalogs didn't turn up any suitable, affordable, metal bulkhead fittings... just incompatable with diesel plastic, expensive stainless steel, BSPP threaded, and other not-quite-right fittings I gave up.
I'm sure a bulkhead fitting compatable with diesel is out there but I sure don't know where it is. Stainless was the closest I came, $112 for a 1/2'' fitting, even then the gaskets were listed as not compatable with diesel...