Hot, indeed. It was around 90 in Ashland when we were there on 9/12 and 9/13. But it's a dry heat. Definitely bring a warm bag. Five years ago in La Pine it got down to 28 in early September.
BTW...I suspect the ACA route from Butte Falls to Ashland is the same as what we did on CO. I don't remember seeing anything in the way of food between those two points. I do remember at least one campground (an equestrian one) that had a water pump near the entrance. The cafe in Butte Falls has great pie. Here is a link to the map for the day from Prospect to Ashland (you can click on it and enlarge):
Check your brakes before the descent starts on Dead Indian Memorial. It's at least nine miles and includes some moderate switchbacks. There is also at least one cattle guard. But it's really fun with nice views. Just be glad you don't have to ride back up it like we did when we left town.
I wouldn't feel compelled to go around Crater Lake. Plus is damn hard. There are some nice views from the viewing area right where you hit the rim road after you climb up from Rte. 138. There are couple of other viewing areas as you ride counterclockwise towards the lodge before heading south out of the park. The views from the lodge area are great, too. If the ACA route goes to Prospect the same way we did, the descent is terrific. Thirty miles to one degree or another:
Don't miss the gorge where Rte. 62 turns left at Rte. 240.