I live in Prince Rupert and yes we do have Taxis. I would just get one from the port and take to Butze and just arrange with them a pick up time. It is a nice walk through the rainforest but may be a little steep for the toddlers. My DD has been doing it since she was 3yrs though so it should not be that much of a problem for them.
Any other questions feel free to ask. I agree though there is not much to do here.