Keep your eyes on the road ahead. Whatever you piled on the back stays on the back—up the hill, across the field, all the way there.
That changes what you're willing to bring. Stack higher than you would on an open deck. Load the loose stuff (firewood, water jugs, buckets), and just pull.
It doubles as a rail. Clamp on a fishing rod holder, an umbrella mount, a fan—anything that uses a standard tube mount.