There's a campground at the Cathlamet Marina - mostly RVs but I've seen a few tents there.

A lot of folks camp out on the upstream end of Tenasillahe Island - used to do that myself in the days of small, slow boat and no spouse. With the price of gas, large fast boat, spouse, and daughter in private college I may be reduced to doing that instead of driving back and forth myself! eek
_________________________
The fishing was GREAT! The catching could have used some improvement however........