Hi, KJ ...
You will find that formal nights on an Alaska cruise aren't as foo-foo as on Carib cruises. I don't know why that is.
My #1 solution to this is a pashamina shawl in a neutral color that won't fight with any of your dresses. They're lightweight and beautiful. And expensive, but worth it.
Can't you manufacture a birthday or other gift-giving occasion pre-cruise?