I was out there late July 4 years ago fishing from a private vessel. Had a blast and caught our limit of hali and salmon easily.
The road into the valley is steep at 12% grade in several locations and up to 18% in one short stretch. It's less of an issue these days as large fuel trucks still haul in weekly. I did see several RV's and trailers being hauled in/out. I think trailering less than 30' behind would be ok, but anything longer would get sketchy. The worst would be towing in/out and meeting up with an opposing fuel truck or semi on one of the 3-4 narrower corners. There are provisions for pulling over, but you would need to pay attention.
As for the fishing, I personally would not want to charter daily out of Bella Coola. Most of the good fishing is 50 miles out from the marina in the Bella Bella/Shearwater area - absolute heaven out there. The issue with Bella Coola is that it lies at the furthest inland point of the North Bentinck Arm of the Burke Channel. The fjord is somewhat narrow and very deep (I believe 1800') with no holding water for salmon to feed. So you must drive out at least 18 miles of often rough water as the winds blow eastward into land right up the length of the fjord. However, once you exit the North Bentinck Arm into the larger Burke Channel you can hang a right, behind King Island and get out of the winds. From there you have relatively protected passage along King Island all the way to Denny Island where Shearwater is located. Alternatively, if the winds are light you can proceed straight out the Burke Channel and end up in Fitzhugh Sound (Hali anybody!).
I was lucky to stay on a boat for 5 nights (which was a good thing as the boat speed was 10 miles/hr max) so there was no need to charter in and out every day. We anchored and fished as we went along our way. I know there are charters out in the Shearwater area (they have a grocery/liquor store too!) right on Denny Island (IIRC). I imagine most people fly out to Bella Bella and get picked up by charter from there.
Good luck with your research.
here is a pic of the road in called the Freedom Road:
But once you are out there: