If I had your limited time for a trip, I would fly to Seattle, take the ferry to Juneau, take 2 day AMHS trips to Sitka (my favorite Alaska town) and Skagway (my least favorite town in A!aska), then fly to Anchorage. As suggested by others, rent a car/truck there and drive to Denali, Whittier, and Seward. Take the Denali bus tour and the Kenai Fjords NP boat tour. You will have then seen all the places the cruise ships go except Glacier Bay. And it will allow time for the weather in South Central to warm up a bit.
When you have more time, you can go back to see Fairbanks, Valdez, Homer, Haines, the Denali Highway, the Yukon, etc. By then your DH may have realized that Alaska is not really a third-world country, despite its size, and be willing to take the RV!