I haven't biked either route but have lived in the Eureka area for 40 years and used to live out on Hi 36 before that. I'd much prefer 36 as B. carfree suggests, and do find it to be quite beautiful. When you cross the south fork of the Trinity river at Forest Glen there's great FS campgrounds and the river will do quite well in lieu of no showers. There's no resupply in Forest Glen so Dinsmore 20m back is the nearest store. I can't remember if there's much of anything beyond FG till you get to Red Bluff so you'll need lot's of water.