Zum said:
I was wondering about conduit but it would be a pain to notch them ribs to run that.
I was thinking the same thing. I used outdoor grade PVC conduit in mine, which may bend enough to thread behind the ribs, but I don't know if you have room for it. You might consider finding some plastic tubing or such that will fit, for fear that vibration might cause the aluminum edges to cut into the wires over the years ahead. At the very least, run a file or something over the edges to remove any sharpness.
Don't take this as an insult, I think you are doing a great job! I would just hate for you to have a short circuit spoil a trip for you down the road.