You'll be into the winter schedule in October and the service becomes very spotty. The only way to bypass Canada is to take the cross gulf ferry from Juneau to Whittier or Homer but I don't think it runs on the winter schedule, at least not often. You really don't want to be on the Gulf of AK during a winter storm. I checked earlier this year and a 25' RV with two seniors and a cabin is just shy of $10,000 round trip Bellingham to Juneau. IIRC round trip Juneau to Whittier as another $6,000 or so. Even if you had money to burn the winter schedule will likely not accommodate your travel.
We use the ferry from Juneau to Haines almost every summer since 1987 for a trip to the AK interior. We are able to cross the border in spite of Covid restrictions because we have medical appoints in Anchorage that we cannot get in Juneau.
Until they open the border for vacationers I think you are just out of luck now.
The AK ferry system is hugely under funded and service has gone down the toliet in the last decade or so. Prices have doubled in that time and is no longer viable for long trips. For our 25' RV with us two Juneau to Haines is 90 miles, 4.5 hours and this summer is $750 round trip.
At 25' the price more than doubles the 23' price. There is no logic in that!