I used to fish the river in the 80's, I'm sure things have changed some, but here is my take.
The early run, at the end of May brings in the biggest fish, but are few and far between. The black flies will eat you alive in early June. The July run of bright fish are the most active when hooked. The fall is the best chance of hooking up because there more fish in the river. It is also the most beautiful time on the water.
About camps; They can get expensive, but you can also meet like mined anglers and fish private camp waters. The guides have good knowledge of the pools as they work for the camp. Usually it's an 8 hour day of fishing also.
DYI; I used to stay in boarding houses or B&B's. Some even have guides they recommend. Best chance to learn the river and move around.
Guides; They are good and bad guides, I've had my share of both. I've learned the first thing I ask is "are you a salmon fisherman?" If they say no, I look for another guide. I'm also up front about what I expect from them as far as time on the water. It doesn't hurt to say there will be a bonus for late hours. A good guide will also have access to some private water, when camps are in between sports.
Good luck, it's a nice river.