Sure it can driven all the way. There aren't any parts that would be difficult for a big RV. You have a few grades on the east side of the Sierras (north of Bishop and Mono lake), some freeway sections around Reno, good 2 lane across northern Calif and OR. Some low mountains in northern OR. Mostly freeway to Spokane; more 2 lane to the border.
In BC you meet Hwy 3, Crowsnest, which crosses the south side of the province. The drive east from Christina Lake has a scenic grade (2 if you go all the way to Creston). West bound there's good downgrade to Osoyoos. 3 is scenic, but can leave you feeling like a yoyo if you drive all the way across.