Every national park website recommends canoes are "NOT" used in estuaries anywhere north of Rockhampton. The advice should be taken as sound advice. People are taken from canoes by crocs. SImple. Infact Lakefield national park has signs about it everywhere yet someone decided to ignore it and was taken.
It is a two fold problem. They offer no side protcection and they look like a crocodile from underneath, so even a territorial attack can be fatal. Also the rowing action is the very sound crocs are attracted to.
Don't want to put a damper on your adventure but please take some sound advice. I live in croc country.