I have experienced some slow fishing there also. The best fishing I have had was in late July & early Aug. Those fields are full of hoppers and it is nice to change up styles some times. It is very beautiful there!
I second the warning on bears. Last time I stayed at the campground the rangers had to bait one into a trap right in the middle of the place. I did stay one night at BC #40. It was nice enough. I don't remember it being spectacular in any way. It is worth a shot for fishing. Try to wait until the temps get up if you can.