I live in Nova Scotia Canada,I have Good Sam and had to use it only once but was pleased with service.It took about an half hour from call to tow truck showing up ..Can’t speak about the rest if Canada or Alaska but I would call Good Sam directly and have a conversation with customer support about their coverage areas in which you will travel.
We went to Alaska this year and spent over three months there. You will find that most RV parks offer GS Discount but be prepared for higher cost even with discounts. Also fuel cost traveling in Canada are higher. I felt like I got a pay raise when we crossed back into the lower 48.