On one of my trips to Belize, I took Canadian money too thinking that the exchange would be no big deal. Wrong. My thoughts of Belize, Cananda both commonwealth nations, the exchange would be a no brainer, wrong. Why ???
Reality is only an illusion that occurs due to a lack of alcohol
The other point that you missed is that the majority of Canadians travel to foreign countries with US currency. We know that it is accepted. Canadian dollars generally aren't even accepted in the US.
Off topic. A big difference between Belize and some other Caribbean countries is that Belizean merchants give change in Belizean dollars when paid with US$, whereas many merchants in Jamaica, Dominican, etc. will give change in US$ when paid in US$. Much easier for the traveller to get US$ back.
Moose Keep an open mind and something good may fall in.