Things will get a lot quieter not only in Alaska but in the Canadian provinces you pass through on your way home.
Labour Day weekend is usually the last camping weekend for most people in Vanada and their rigs get parked right after that.
As well a lot of campgrounds will either close or start to wind down for the season. A lot of BC Probincal cmapgounds stop taking reservations on the labour days weekend and "some" close off parts of the campgrounds so that they don't have to mainatain the entire park.
This being said. You won't have an issue finding a empty spot in the campgrounds that are open, and you most likely won't find them full with fellow campers.
I know where we camp the campground is just about empty and if the weather cnages we have found that there are only us seasonal campers left in the campground.
Also where we camp and the campgrounds around us are cloaked by the end of September this is including BC provincial campgrounds as well as private campgrounds. So by the end of September your going to have a hard time finding a campground open. I not saying there isn't any open after the end of September but they will be few and far in between, around here anyways.
So you may want to do some research on routes heading south and see what's open for the time period you think your going to head home from Alaska.
Soup.
2018 Northern Lite 8-11 EX Dry Bath
2017 Sierra SLE, 3500 HD / 4x4 / Duramax with a 6 speed Allison Trans
Torklift Super Hitch 20K, 48" Super Truss, front and rear frame mounted tie downs
Fast Gun Long Range SS Turnbuckles, Fast Gun locks