In 2011 I purchased an Extang hard fold cover and it is great, larches on each side at the front using built in screw clamps. With the tailgate open there is a spring clamp on either side that locks simply and securely then shut the gate and lock it. I transfered it to my 2015 Canyon and now to my 2017 Denali, cover looks as good as first installed. I needed new trim rubber for front of bed and Extang sent me front and rear pieces at no charge arriving in three days.
This cover can be folded and secured for tall loads however a third of the bed remains covered.