>>686562The Cassiar Highway is in BC, south of Whitehorse rather than further east.
I'm sure you'll be happy enough doing your trip your way, but one final word of wisdom. Alaska is fucking huge and full of wonderful places to go /out/. You could easily spend a week in any corner of it. It can take forever to drive from anywhere to anywhere else thanks to all the road work that needs doing.
If you want something low-key and day-trip based, a day or two hiking in Kenai Fjords NP and half a day on a tour boat out of Seward aren't too bad.