G'day cassgazz,
Bit of common sense and you'll be right, stay away from deep dark waters (shouldn't be wanting to drive into these anyway)...... if you can see the water isn't too deep, can sort of make out the bottom where you're intending to cross and a bit of a distance each side, you should be right.
To give you a bit more confidence, most of these water ways are crossed on an almost daily basis during the dry,if crocs had been seen at the crossings it would be well reported.
Still doesn't hurt though to have someone back at a highpoint keeping an eye out, just to be really safe.
Like Teabag mentioned there are a few creeks/rivers that are real no go zones, he mentioned the Wenlock, funnily enough a mate of mine from Weipa was in the Wenlock last weekend flicking a few lures from the bank, his nose picked up a bit of a stink, anyway as he wondered along the bank he came across the front half of someones dog floating against the bank......
Good luck mate,you'll be right, enjoy yor trip.