Ideally, in my not-really-that-humble opinion, one should take a separate trip (not even necessarily an "RV" trip) to "do" Southeast AK. Take the Alaska Marine Highway ("ferry') from Bellingham or Vancouver or ??? up North, i.e. to Juneau, then fly back or something similar.
My view is that combining a road-based tour of Southcentral (i.e. Anchorage) and Interior (i.e. Fairbanks) with visits to SE Alaska (which is mostly accessible via air and water) creates difficult (which means $$$) logistics issues....certainly do-able, but makes for a long and time-inefficient trip.
If the daughter is interested in seeing Juneau (or Sitka, or Ketchikan, or Petersburg, or ...), a suggestion might be for her to fly there after the joint trip with y'all then she could spend a day or two doing the local tours then fly home.