We do the Oregon Coast from Astoria to the California border almost every two years. At 65' I have no issue driving fast enough to keep cars from stacking up. Many are turning on and off the highway and there are passing lanes in between.
I've driven California 101 too, many times, still no issues.
When driving some of these roads, you can't be frugal and occasionally need to throttle up, rather than worry about mpg. Take the turns at the speed your comfortable with, but throttle out of them, rather than mosey out of them. On some of the roads, like Hwy 41 into Yosemite, between the entrance gate and Yosemite Valley, I'll drop into third or fourth and leave it there. It eliminates the up/down shifting and gives you constant power.
On the Oregon Coast, there are many turns and areas with short hill climbs. This is where you need to stay on the throttle and power out of turns. The turnouts are plentiful, but are all on the ocean side. So if you're going north you'll have to watch for openings to cross over.
Also, be prepared to hit some cold and rainy weather, the Oregon coast is best visited during late July and August. Lastly, make plan's for a night or two at Golds Beach. There is a campground there called Turtle Rock, nothing exciting, but it will fit your rig. Just down the street in town is Jerry's Jet Boat Tours up the Rogue River. You won't be disappointed with the lunch or dinner excursion. Might want to book a day in advance.
