You will want to call the Alaska Marine Highway (ferry ) when you are able to determine the
total length in feet of the rv and trailer combined...only then will you get the bad news on the cost on the ferry, especially from Bellingham Wa
The cost of your RV & trailer combined from Bellingham to Haines is $67.20 per foot...so lets just say the combined footage is 45'..the cost would be $3025.00...
Through April 30th the driver goes free
Adult Fare...Bellingham to Haines is $353
Children under 6 go free...age 6 to 11 go at 50% of the adult fare...over age 12 is adult fare
So...you could easily be looking at $3500+ on the ferry to Haines..
Couple options....catch the ferry at Prince Rupert BC instead...it takes a ton off the cost of the ferry and for you driving cross-country it is very easy to cross over into Canada and continue west and end up in Prince Rupert...at Rupert you can board the ferry with your final destination being Haines...from there its 750 miles to Anchorage
The best option....again cross over into Canada in your westerly drive and when you get to Prince George BC just simply head north to Whitehorse Yukon..from there its west to Haines Junction...from there its north to Anchorage 600 miles.....its all very good road from Prince George north and there are plenty of services all along that route...and the country will be something you'll never forget...
The cost savings will be huge if ya stay off the ferry system.....the ferry is very boring,
especially with kids...3 full days from Bellingham to Haines...the rooms suck if you can afford one and the food service onboard is very costly also...you are not allowed to be on the car deck or use your RV while the ferry is underway...
Order a Milepost if you opt to drive....
The MILEPOST: Alaska Travel Guide and Trip Planner - Home
Also.....there is a poster here that did a similar trip to the Fairbanks area with vehicles and kids (megensmom). Its a good read...ran 56 pages
http://www.city-data.com/forum/alaska/155927-given-home-central-ak-planning-moving.html