Hi Neil, RIB will be OK. Just use your common sense. Besides the croc issue, there are many places where you may want to go ashore up against rocks, where at full tide you may not see barnacles, oysters etc. on the rocks, but as the tide recedes, its likely they will be there.
Think about taking an “anchoring off” system. Have a look at https://kccyc.org.au/topic/dinghy-anchoring/
Also be careful not to get beached on an ebbing tide. You will struggle to drag a 4.2M RIB down a beach to the water.
Cheers, Ross