We thaw early here, it is the banana belt. Clark Fork is usually runnable except for about a 1 month freeze, maybe longer.
The raft shop in missoula are non existent. Trailhead sells some but stocks very little. One of the fly fishing shops is advertising a big show, so you might check that angle. I think it is the one on N Reserve, somewhere in the vicinity of REI.
I am a river, babe - I've got plenty of time, I don't know where I'm going, I'm just following the lines..... - "We are water" by Shaye