The tubs you mention are great until your croc is about 1.2 meters, then you need bigger. The code of practice is a guideline not a set of rules, however they do detail the minimum space required, not the average. Both Fresh and Salt water crocodiles can be kept, if you want to keep one for a long time go the freshie, it is slower growing and smaller in over all size, a saltie will need a much larger enclosure within about 3-4 years. Our 4 year old croc is about 1.8m and needs plenty of space.
Also remember that there is the statement that specimens over 2m should be dconsidered on a case by case basis, this statement is just a guide for DSE, not for the keeper, there is no record of the size of your crocodile, DSE will not know the size unless they visit! In Vic there is NO size restriction.