Why would you ever cross from the mainland into Vancouver Island? You didn’t say you were exploring the Island.
Are you planning on ferrying up from the L48 or driving up?
You can drive from anywhere in the L48 to basically anywhere that has road access in AK without using a ferry.
And fwiw, most all ferries, including AMHS, WSDOT and BC Ferries all handle semi trucks. You can hitch a ride. You pay by the foot!
Regarding which roads to avoid? I’m going to presume you haven’t actually mapped it out. There’s only 1 way up save for whether you take the Alcan or Cassiar through northern BC.
And AK has like 6 highways and not really 2 different ways to get to the same place except from ANC to FBX.
If you’re just hatching this plan now and plan to go in 3 months you must be planning on boondocking the whole way and no substantial reservations. Otherwise it’s gettin to be too late for a lot of substantial 2025 reservations.