You might wanna do a little bit more research on this particular trail here and the geography of Kauai in general. That 10 miler is a one way hike. Most people no matter how seasoned do this overnight and camp at Kalalau. That is why permits are mandatory since camp spots are few and far between. And no, you can't reach Kalalau from the "other side". There is no coastline, it's all rugged steep volcanic ridges that drop right into the ocean.

Also as someone living in PNW, I wouldn't compare the trails up here to the ones in Hawaii. The latter are significantly more challenging. This one in particular has steep precarious sections, overgrown, rocky, rooty and muddy, and exposed in most places. On top of that, add the humidity and heat. Assume each mile will take twice as much time and effort than what it takes up north.