Idaho Spring Season
You know where the South Fork is, just a few hours west is the Salmon. There's a huge ice jam on it now, completly frozen over for about 15 miles, but it will be open for your time frame and your spey rod's the name of the game! If there's no powder in the forecast then there's lots of Wyo. 22 license plates along the river. Plenty of steelhead from the Yankee Fork to the Middle Fork and they're not all black and scruffed up.
Several hours northwest and you're in the Clearwater Caynon and the big B's, a trip of a lifetime. Idaho sells a 3 day non-resident for @ $35 or a full year for twice that.
Both rivers are beautiful and you need to explore them. There's plenty of campsites, steelhead, hot springs and skiing.
Spring time in Idaho, your skis are on your feet, your spey rod's in your hands and your fartin' though silk panties!