There's probably room for a couple of more tents in addition to the level area south of the lake outlet, if you aren't too picky about perfectly smooth ground. I'm sure the lake is thawed out by now. The place is getting popular though, on our way down a couple of years ago (a Saturday) there were many parties going up to camp, and I was wondering where they were all going to set up.
Also it's worth researching the tides before you go, something that I didn't do on our last trip. When the tide is high there is less current in the river. We had a nice easy paddle on the way there but in the afternoon when we came down, we had a hair raising paddle to get back to the other side.