I would pull the screws on that under seam, odds are water has pooled in there from clearance lights or window seams. I wouldn't be surprised to see alot of water come out of there.
If it does drain, you'll need to unseal the siding and peal it back to let it dry out and then treat the wood if its still intact, once its fully dry.
I would plan on needing to re-bed the clearance lights, and recaulk them, along with all the gutters, corner moldings, windows, vents, etc.. etc....
With your standard RV, you usually need to recaulk them every two years.