I just completed a round trip from Seattle (actually I started in Corvallis, Oregon) to Anchorage Alaska. (We left 19 June and I drove back 5 July). If you count one way as one trip, this was my 27th trip, starting in 1965. (at that time and for several years thereafter, from about mile 80, out of Dawson Creek (the start of the official 'Alaska Highway, or ALCAN) is was gravel all the way to the Alaska border (about 1,200 miles) Now it is all paved.
I go East a ways (from Bellingham) to cross into Canada, at the Sumas, WA crossing. There is a really nice little campground just 'up the road' a ways at Hope, BC, called "Wild Rose" campground and RV, which I can really recommend. From Hope you go north through the Frazier River canyon.
About 19.9 miles north of Cache Creek (which is a small town just after you come out of the canyon) there is a campground called "Willow Springs". (It used to be called "Lakeview Campground".) This is the first place I stopped when I drove north in 1965. The campground is right by a small lake (there are larger lakes nearby with good fishing) which has free 'foot-paddle' boats for campers to use, non-metered showers (please don't abuse) and many nice spots, some in the tall pines.
This campground has changed hands several times and the present owners are working hard to overcome some years of neglect. I stayed there a couple of weeks ago and they are making a lot of progress. They have RV spots and quite a few van, tent type sites. I would urge you to give them a try and help them out a little so they can get going.
The highway over all, was good, some construction, naturally and unfortunately for us tent campers it rained the last couple of days going north.
Any questions I can answer I will happily do so.