I don't hike but my experience I can share my experiences with longer walks with my two. Magnus (5 y.o. 16 lbs) LOVES to walk and will go for as long as I can last. Zoey (4 y.o. 5.5 lbs) is a different story. She either gets tired or doesn't like the area or who knows but wants to be carried during the walk.
I got tired of carrying her in my arms so I bought a backpack to put her in. SO MUCH EASIER and safer. Here's a picture of her in the backpack. She loves it!
http://www.yorkietalk.com/forums/att...y-backpack.jpg