i did the Gibb in my 07 d40 a couple years ago in the tail end of the dry, (late september) no snorkel, 2 inch lift, 30 inch tires, stock transfer and gearbox breathers, extended diff breathers and had no problems, the pentacost river was only 30-40 cm deep and was an easy crossing, some of the streams in El questro where deeper, but not much,
take 2 spares though, i tore open 2 tires in 30 km at bells, went and saw Nev at over the range he sorted me out
seriously take 2 spares