TrailBeast said

Once I had a fender on for the final installation I sprayed the underside of that seam with undercoat.
We don't want road water getting between them and the inner fender, and it doesn't hurt to have that protection from little rocks off the tires and moisture on the inside of the fenders anyway.

The strip or roll stuff doesn't let the seams come all the way together between the bolts.

Click to expand...