“I was surprised that it doesn’t appear to reach Crater Lake, which would help a little.”
It’s all uphill to the south and Crater Lake, and only slightly downhill to the north.
At -70 m HAAT 26 m HAG it shouldn’t be a surprise.
Besides, a class A isn’t supposed to go over 17 miles to the 60 dBu.
Crater Lake is at least that far to the northern rim alone let alone the whole lake and southern campgrounds.