When I was driving rubber buses down the river I used to ask kayakers to splat my raft for my own entertainment. I only ever had a few oblige...
Splatting your own raft is indeed a necesary part of boating. That is why a lot of rafts are now coating their bottoms with urethane this makes the rafts slide up rocks better.
Andy I agree, that rock above hecla is good for backloading and splatting away. Pillow is great, as well as postage due. There is a rock below the gorge above grape creek I think on river left at lower water is a great splat, have seen many overzealous guides turn them over there.
Have fun out there, and keep your grubby kayaker hands off my beer, but I guess if you can grab it while splatting you are more than welcome to a cold one.