Yes, I wired the H3 this way. We have an SUT and an H3... and another H3 on the way.
SILL plates, not steel plates. A sill plaste is what you step on when entering your vehicle. You can run the wires under those (by each door) and than you just have to figure out hw to pop off the back pannels to get all the way to the back. But there should be pleanty of room for your B/U cammera wires to go back there. I would run your CB antenna wire from under the dash, out that side boot and up the A pillar and down the roof track. Firestick has mounts that will mount in your factory track. PM Phil D from Trailduty and he can point you in the dirrection for that mount.