It's a beautiful ride. As suggested, stay in Klamath Falls and drive out to where you want to start. Look here if you want to see what awaits you; it is stunning. I rode the Crater Lake Century in 2007 and am saving up to go again (I live in Virginia). It may be the best road ride I've ever done.
http://www.steephill.tv/galleries/2005/crater-lake/