Upload & Sell: Off
I've never rafted the "Tat" but I've rafted many rivers just like it. You will likely experience sweeping vistas, wildlife (lots of eagles), and tons of other interesting stuff like macro subjects to photograph. At the end of your float there is plenty of floating glacier ice. You must be prepared for lots of rain. Did I mention how it will rain a lot?
If I were going on that trip I'd have along my 5DIII and at least one of my 7Ds along with the 100-400, probably the 70-200 F2.8 II, a 16-35 f2.8II, and maybe my 100 macro.
Have a grand trip!