California HWY 49

I drive that portion of 49 regularly. There are alternative routes from Placerville to Auburn and still take in most of 49. First heading North, take Green Valley Rd. West to Lotus Rd. Head right on Lotus Rd. It will drop you out at the South Fork American River bridge onto 49. Go right and you are a couple miles from Coloma and the 1849 gold discovery site of Sutter's Mill. Lots of stuff to explore around there and white water rafting in season. Go left and you'll head North on 49 to the town of Cool. From Cool to Auburn is twisty. However, I seem to always be following either a loaded logging truck or a truck-n-transfer of gravel from the Cool gravel pit. If these huge rigs drive this daily, and the local traffic knows to expect 'em, then an RV, even with a toad, isn't gonna sweat it out. Besides, that section is only about 30 minutes long. As you head out of Cool and drop into the canyon, the primary view is of the North and Middle forks of American River. The bridge is at the confluence of these two. Go left and it takes you into downtown Auburn. Go right and it will take up to the Foresthill Bridge. Movies are filmed there, one of a sports car being driven off. Many base jumpers use it as well. It's less traveled than turning left, so I recommend that.
So basically you would only be on 49 twisty from Cool to the bridge, maybe 10 miles tops.