Deerslayer,
Do I need to document what food we are bringing with us?
Answer: No, not necessary. Be prepared to answer verbally, “What food stuff are you bringing with you?”
Don't plan on bring many vegetables, maybe some potatoes, will prolly by a little local produce once there.
Answer: Leave your potatoes at home and buy once you get into Canada. Lots of regulations on bringing U.S. potatoes into Canada and most likely would NOT be allowed to enter with taters.
Other question, regarding alcohol,
I will most likely need more, how much is the tax to cross with an extra case of beer or a extra bottle or two of alcohol, like for example, rum?
Answer: The Canadian fees on alcohol over your standard exemption would be more than what you originally paid for the alcohol. Best advice is to bring the amount that you are allowed and purchase any EXTRA that you might need in Canada.
Canada is a great place to RV. Enjoy your travels.
Lakeside