"do you need special insurance or is the dfo boat inspection it?"
Not sure I would try to charter out of my own boat without checking around about insurance. Standard policy we all usually have may preclude or not cover you if you are using your own boat.
If you are "guiding" using another charter operators boat, such as out of one of the fishing lodges, they would have you covered.
Maybe some our members who are charter boat operators can give you advice.