That's 690 km a day every day ....I'd not try for that tho you can put in big days on the slab to get to the nice areas.
You do need to have time to see a few things, rest days etc,. Where are you riding out of ? What is he riding,
We averaged 450 km a day and had a rest day, ferry ride and two days left at the end. ( we did three weeks but flew the bikes Toronto to Vancouver - so that saved 4 days ). We did not do Alaska except to touch at Hyder part way up the Cassiar ( must do ) they ferried over to Vancouver Island - no way we could do Alaska in our time frame even with flying the bikes to Vancouver
You really want to target Valdez and the Kenai if you are sightseeing at all. 99 north from Vancouver, Bow Valley between Banff and Jasper, Glacier Nat'l park, Hyder/Steward, The Cassiar, Muncho Provincial Park, Takeetna Air Taxi service ..take a flight - land on a glacier or circle Denali ( $$ but worth it )
Top of the World is treacherous in the rain - Chicken is fun tho - Denali Park is "okay" ....don't knock yourself out,
Kenai and Valdez are so gorgeous and lovely rides you should focus and only skip if weather is bad ( fairly common )
You cannot count on steady riding as long stretches of construction can kill you average and they a muddy as they are watered 10-20 mile stretches are not uncommon.
Deadhorse /Dalton will use up at least two days ...maybe more as 414 miles of "can be brutal" gravel each way.
That's likely to be your go/no go decision - and if you breakdown it's an expensive and slow recovery ....the road apparently is very hard on tires. You should read the ride reports.
Even with an AWD...we decided not to do it but went to Yellowknife instead,,,we had 5 weeks on that trip and two drivers and decided not to cross the Arctic Circle
....300 km short at Fairbanks.
If you are riding the same bikes or even if you are not - a set of spares ready to be shipped to where ever you are might be worth it...as one breakdown halts you both and you can easily be stranded for a week. Patchkit and compressor a must. There is not much in service outside the main centres and you need to carry spare fuel.
Kid ran out even on a main hwy and of course the spare wasn't full....you'll appreciate the Strom's big range. Some stations are seasonal.
Milepost Guide for year you are travelling is a must have.