Salmon river in Idaho
Check out the Salmon River in Idaho. 100+ miles of class II-III+ options from Stanley down to Corn Creek, all permit free, river is mostly roadside, plenty of cheap and/or free camping options, warm water by mid summer, little to no river traffic on weekdays and minimal river traffic on weekends. The Salmon river is akin to a ghost town compared to Lower Canyon on the Snake River near Alpine Jct. 99% of Salmon river road traffic is folks heading up to or back from the Middle Fork, or to launch on the Main Salmon permitted stretch. The areas include some fun and interesting history (mining, Lewis & Clark, etc), excellent scenery, etc.