You should also contact your cruise line to see if they'll even let you board at Ketchikan. Assuming this is a departure from Seattle, and assuming it's on a major cruise line, then boarding at Ketchikan exposes the line to serious fines and penalties as it would be a violation of the Passenger Services Act (sometimes erroneously referred to as the "Jones" Act - which actually refers to cargo handling and routing.)
Seattle departures are all "round trip" routes with the same US city as origin and destination, which under the terms of the PSA requires foreign-bottom ships to make call at a "foreign" port at some point during the cruise; this is why you'll stop in Victoria BC on the way back.
By boarding at Ketchikan, that turns it (for you) into a one-way trip between two different US cities (KTN and SEA) which under the terms of the PSA requires a stop in a "distant" foreign port, of which neither Canada nor Mexico qualify. This is why one-way trips to/from Alaska (say, Seward or Whittier) all depart from Vancouver BC - foreign to domestic or v.v.
Some cruise lines will submit to the fine (I forget the amount, but in the hundreds, maybe a thousand dollars or more - per passenger) and then pass it on to you; others may just refuse letting you join at some intermediate port of call.
I'd really try to move your flight arrangements, and at a minimum I'd read the insurance policy T&Cs to see if this would be covered. But first I'd call customer service at your cruise line and get the scoop on their policies.
Edited to add: Your options for getting to KTN are one - fly, on Alaska Airlines. That's it.