Agreed on waiting to activate the PLB, as long as you're equipped to wait it out. Again, my impulse is to stay in place at or near my vehicle, or at or near a place of civilization is its nearby - but in overthinking mode, if you had to cross a river, having a PFD and a rock helmet in the trunk of your car would be small and reasonable equipment with which to attempt what is surely a life-threatening Western river crossing. You can actually participate in some white water rescue training, I did this on the Snoqualmie 30 years ago, basic advice though is lean back, don't try to keep your head above water, and swim like hell at 90 degrees to the current when you hit a break in any rapids. It can be incredibly tough, and you may not make it alone. Weigh your options carefully. Your odds of making it out of the water go way down without a PFD and helmet. Its such a remote possibility, I honestly wouldn't put mine in the trunk for a road trip in this or other remote areas, but in terms of space requirements, its alot less than hauling a boat...

Two other obvious observations - drive as far as you can in the direction you want to go - if you hit an obstruction, you have fuel and you can drive in the opposite direction to see how far you can go there too, then return to the first obstruction if you want to go further in that direction. If you hit an avalanche, you need to assess for stability and further avalanches before crossing. Take your time, make sure, rather than getting buried and trapped in after fall. And I know from experience, crossing an avalanche area with your bike can be an ordeal, so you might lose your transportation if you cross.