Welcome to the forum dutchwheelz. I'm new myself.
I tried a harness and it crushed / interfered with my cables so I just strapped
a drybag on using the cables to keep it from flopping.
I
haven't tried these bags on the trail yet. I just started converting this bike to a gear carrier.
I hope to have a trail report soon.
The drybag is a 10L and it holds my spare clothing and rain gear.

Adding a Jandd handlebar bag(the strap only model no handlebar bracket)

and a Jpaks gastank and snackbag
