Having difficulty computing the cost from Bellingham to Haines with my set-up in my signature below. Overall length will be 56' with bike rack attached. When entering info, the Ferry website gives...
I'd suggest taking a great 4-5 day drive from Camano to Prince Rupert and taking the Alaska Ferry from there. You might cut the cost in about half.
In 2014, our 22 foot truck camper cost about $1200 from Prince Rupert to Haines with layovers in Ketchikan, Juneau and Sitka (separate side trip to Prince of Wales Island from Ketchikan).
I'm not sure what you would see between Bellingham and Prince Rupert anyway.