Erik,
I've fished the Big Su a few times in the last couple of years (I'm assuming its the Big Su you're headed for). All the king fishing I've done entailed launch and heading for one of the tributaries of the main silty flow. The Deshka was one trib we hit with good success pulling out Kings to 63 lbs. The style of fishing wasn't to my liking. It consisted of anchoring in the clear waters of tributary mouth, with umpteen other craft and casting plugs to milling fish which pulled out of the muddy water for a clean drink. While the fishing was good (usually a one fish per year per trib limit) the crowds were large and foul ups were common. I've fished the Little Su in August for silvers and encountered fewer people than you'd see up on the Big Su at the mouths of Montana or Sheep Creek near Talkeetna.
Alaska Flyfishers has a good website and a BB similar to this one where you could get some current info on all the waters in that area.