We have a Born Free RSB also, a 1999 model. Traveled to Alaska in 2009 and are planning another trip this year. We don't pull a toad, and as far as the Alaska trip the only time it would have been of some use would have been in Anchorage and Fairbanks but even then not a big deal.
The ferry is good especially if you take time to get off to visit the towns on the way. As mentioned, much cheaper to use Prince Rupert than Bellingham and you still cover the prettiest parts. But why the ferry both ways? You say you're full timers, why not start early and take it easy and drive at least one way?
We go up through the Canadian Rockies (Banff & Jasper) and the Alaskan Highway and come down the Cassiar. Mosquitos are around but not so much as to affect the trip or taking our time. You can miss a lot by taking the ferry both ways.
