We had several CRDs in the SJC Flinders and Simpson Desert Trip last winter. Only one of the JK CRDs had a long range tank, the rest carried a couple of jerrys (as did the KJ CRDs as well). No one actually needed to worry much about fuel. As a rule of thumb for CRDs about 120 Litres should be sufficient for a full crossing (and we carried enough for a full crossing). A jerry can actually hold more than 20 litres (if you top it up at start out, there is at least an extra litre you can get into the yellow plastic ones). Drain the jerry into the fuel tank as soon as there is room to do so. There is alot of information about fuel consumption figures for various vehicles on the Explore OZ website.
Now having said that, the odds of you being able to do a full crossing this coming winter are pretty slim. Last year the Eyre Creek stopped most of traffic getting through to Birdsville via the QAA line from Poeppel Corner for most of the winter due to the flooding. The Eyre Creek bypass only opened to traffic towards the end of the season and really only high clearance vehicles could do it safely even then (so a lift and a snorkel would be in order). With the cyclones and flooding in North, Central West and Western Qld over the past few months, and the flooding frther south, all of that water has to go somewhere. Some of central and western Qld drains down into the Channel Country rivers and streams and into the Cooper then to Lake Eyre, the other big drain is the Eyre Creek system into Lake Eyre.
We were stopped by the Eyre Creek flooding. So make a backup plan.
Even just doing a Desert day trip out of Birdsville can be very daunting due to the flooding to the clay pans, the bypasss needed, and the inability to access Big red without the detour around Lake Napponerica. The Lake Napponerica bypass track was really chewed up when we were there in July, it can take an hour just to get around the bottom of the Lake on that track.
So keep an eye on the RACQ and SA Roads websites, and also the one for the Mt Dare Hotel:
http://www.transport.sa.gov.au/quick...s/northern.asp
http://www.racq.com.au/travel/Maps_a...oad_conditions
http://www.mtdare.com.au/index.php?o...&id=3&Itemid=1
Good luck