I was in Alaska in August. We didn't do a "tour," but rented a car and did our own thing.
We flew into Anchorage and spent a couple of days there. One day, we took the train into Whittier where we do a glacier cruise. Then took the train back to Anchorage. Our cruise was great because we had clear skies and could see all the glaciers.
We used a tour company and went by bus to Denali. We used that same company for our Denali tour.
Would they be willing to rent a car and do their own thing? There are a few places they could visit that would offer some views, but with minimal physical activity.
My cousin and his wife did a 7 day land 7 day sea tour of Alaska. He enjoyed it because he had a hip replacement not long before the trip. The tour guides helped them along the way with getting luggage around and other things. Maybe a tour company offers a 7 day land tour?