It is pretty pricey if you are going over in an RV. The only way to come out in the black is to stay a couple 3 weeks and boondock the whole time. The ferry is out of Prince Rupert on a night sailing for 9 hours. You cannot be on the vehicle deck, so it's either trying to sleep in chairs or taking a stateroom. It's $100.00 well spent. An option would be to take the toad, if you have one, and B&B it for a couple 4 nights. You'd need to park the RV in a paid spot..so..all in all..I'd take the RV.
Haida Gwaii is a place of special things. It is very relaxed...very laid back. If you are going to go..be in touch and I can give you places to go and see. There aren't loads of RV resorts..mostly provincial camp grounds. A dump in Queen Charlotte City and one in Massett.
Gary Haupt