I had a similar issue, a large bundle of wires from the front needed to get to the back wall of my crew cab. So I ran the bundle, protected with wire loom, from the front of the engine compartment, following one of the factory wire bundles, down through the engine compartment and down the frame rail where it met up with the storage compartment under my back seat. On the rear vertical wall of the storage compartment I drilled a hole and ran the wire loomed bundle through that hole. I used grommets on the hole in the metal and actually doubled up that section of wire loom for added security.
that hole I drilled was next to the rear seat bracket, and then ran the wire loom to the rear wall behind the seat. It’s all protected and out of the way. Safe and secure.