I think if you'd made the trip before then the plan to do it again in 30-40 days with only 7 days in Alaska MAY be reasonable. Some of us have done the trip in a week or less in our younger days but we knew what we were facing at the time. Having done it before you'd at least have a pretty good idea of what's in store for you and you'd have a pretty specific goal in mind such as Halibut fishing in Homer.
But, an aggressive plan like this for going into a part of the world you've never seen before may leave you very disappointed over the adventure in the end. The scenery and wildlife in BC, the Yukon and Alaska are unlike anything you're every going to see here in the Lower 48 and until you've experienced it you just can't imagine what you'll see. That's one reason you see a lot of people who make plans for their once in a lifetime trip to Alaska, then having done it immediately start planning their next one. There are 100's if not 1,000's of places along the way in both Canada and Alaska that you'd probably like to spend the entire 30-40 days at once you see them.
Don't mean to be a wet blanket on your trip plans. I'd really like to encourage everyone to visit and spend time in the land of my childhood, but I also want them to really enjoy it and come away with the experience of a lifetime. In the end your aggressive trip plan seems a bit like visiting Grand Canyon by flying over it at 30,000 ft.