Steve, yours looks like a good idea also. With RCKen's idea it looks like the fuel tubing gets smashed out at the bottom so do you think there is a need for the CA hinge to be glued to the inside of the cowl?
ORIGINAL: Steve Campbell
RCKen's method is a good fix.
Try this: before you do anything else, glue a CA hinge over each of the holes, on the inside of the cowl, with medium CA. Ensure that the entire hinge is saturated and adheres to the cowl. When dry, open up the screw hole to the same i.d. as your pieces of tubing o.d. Use a washer under the screw head, and you've got a quick, easy vibration isolator.