A 6x2x2 aquarium will be sufficiently large enough for possibly a few years (depending on food intake and husbandry as previously mentioned). All our old juvenile crocs were kept in small aquariums, they thrived in small tanks. We tried large landscaped ponds for some of our juv. salties and they stressed considerably, went off food and it was obvious not optimum for their welfare. We had success upgrading to ponds once the juvies hit the "big boy" mentality (flighty to fighty) when they have much more confidence. We saw a dramatic increase in appetite and overall personality when we would put stressed crocs in large enclosures back to small aquariums.
There are a few crocodilian husbandry related books but their detail has only limited application to that relevant to the private keeper. Worth a look if your interested in such but the majority of information within won't be directly relevant to your scenario.
I suggest simple is better. I usually encourage people to provide ample refuge (hides) both on land and water, juvenile crocs are often prey to a diverse range of species so they generally seek shelter/security until they hit the "bold" stage of their development when they go from flighty to fighty.
If it was me I would get an upturned milk crate with the majority of 1 or 2 sides cut out to allow for movement/access, put a solid platform on top of the crate this will serve as a land section and provide an underwater "cave" for security. Add in some additional furnishings but nothing too extravagant, water heaters, filtration and a basking lamp.
For an easy method to provide security to a croc both in land and in water cut some palm fronds and throw them in the tank, they do get used in my experience and are particularly good for managing stress after a move. Obviously replace when necessary.
Google caiman and alligator setups from the states as well, for ideas.
much appreciated.
