299 is the major road connection between the north coast to inland California. It is a good two lane road and for the most part follows the Trinity River between the town of Willow Creek on the west, and near Lewiston to the east. It does go over a couple of mountains:
Buckhorn Summit just west of Whiskeytown Reservoir at about 3200 feet elevation. The climb up from Whiskeytown to the summit is very winding and relatively long. Steeper going west.
Oregon Summit just west of Weaverville at about 2.900 feet in elevation. This can be a relatively long hard pull going east. However, I do it a couple times a year in a Dodge van 3500 15 passenger with a boat trailer and load of people and camping stuff. I overheated once in mid summer when I wasn't paying attention to the coolant level before starting out.
There is a nice campground on the Trinity River in Douglas City (public). This one is away from the highway, a rarity in the area. It is on the otherside of Weaverville from the BLM site at Junction City.
Near Del Loma is a USFS campground, Hayden Flat. There are others scattered around, if you do not need hook ups. Vault toilets, and water available.
The road climbs away from the river east of Willow Creek as the river goes through a gorge. The road get curvy through some of this.
Of course, for some people the lakes (Whiskeytown, and Lewiston) are major attractions. For others, like me, it is the river. Nice clear, cold water, and sections of mild and flat, to very turbulent whitewater.
The two major towns between Redding and Arcata are Willow Creek, and Weaverville.
West of Willow Creek are two more summits:
Berry Summit, at about 2800 feet, and Lord Ellis Summit at about 2200 feet.
There are virtually no services between Willow Creek and the Coast.