This is my second time on the Kings Mountain trail, my husband runs the Elk-Kings route routinely. The beginning of the trail is covered in majestic ferns and the end in wildflowers and views of Mt Hood and Coastal Range. One is deep within the forest almost to the top and this is why we felt it would be safe to take along our very energetic 5 year old. To our surprise he made it to the summit within 2.5h with lots of breaks and a picnic on the way up (and down). The trail itself has a lot of scree so he held onto us for those sections. He did fantastic scrambling. He was equipped with proper shoes and a vest. For a strong single kid with two parents to mind them this is certainly feasible.