Don't worry about parking your RV at any marina or other location. Alaska is so RV friendly, you will be able to park just about anywhere.
If you are in a Class C and have three drivers, with all the extra daylight you will have, you will be able to make great time (relative to road conditions, construction, fires, and other unexpected) and just wake everyone up when there is something that you think they should see. Otherwise, just keep on trucking. After you have made this initial visit to Canada and Alaska, you will have the overview and will know where you want to go on your return trip when you have more time---and unless you are the exception, you will want to return.