We went from Henderson's Line-up shop in Grant's Pass to Crater Lake via the 234/62 roads the fourth of November last. The RV park in Prospect wasn't bad. Could've used some tree-trimming here and there, but it was tolerable. As others mention, this is not country for depending on cell service; We were 100 feet from the office, but I had to stand on the office porch to get cell reception because of the very narrow geographical tower alignment. I know this isn't your route, but offer Prospect's options as they had a good café in town and another popular one a few miles north on the way to the Natl. Park.
There'd been snow at Crater Lake, but we took our Explorer toad for a day trip without much trouble. The road was icy in spots and a few shallow drifts. The Rim Drive however was closed, so we could only make it as far as the lodge, which was also closed for the season. Still some great views, esp. at sunset. Another day trip took us to Diamond Lake.
Upon leaving Prospect, old hands recommended we not take 62 over to Hwy 97, so we went on 138. We knew there was some snow as we'd taken that route to Diamond Lake in the toad, but despite some icy spots to be cautious of and drifted packed snow spots between Diamond jxn. and 97, the coach did fine, as it always has in such conditions.
58 from Eugene/Cresswell is a good road. We have relatives in Springfield and over the decades have travelled it countless times in autos and RV's. In fact we were near there at Davis and Wickiup Lakes 10 days ago. Depending on your exact agenda, and of course the weather and conditions on Willamette Pass, you might consider staying at Big Pines RV a mile south of Crescent on 97, and daytripping to Crater Lake out of there. I believe (from an overheard conversation while at Big Pines) that there is another RV Park at or around Crescent Lake, some 20 miles west of 97 on 58.
Of course regardless of route, dutifully watch forecasts. Be aware that many venues will be closed for the winter. A four wheel drive toad will provide some versatility while gunkholing, but don't push your luck in the mountains this time of year. The sights will be there next year, and aren't worth risky ventures.
-Joel and Lee