I'm looking to get full-coverage fenders for the rainy season on my Giant Contend SL 2 Disc road bike. It has hidden mounts, but the holes are all only drilled through one side and not all the way through. The holes in the fork crown and seat-stay bridge are rear-facing. The fenders I've mounted in the past all had bolts going through and being secured by lock nuts on the other side. Am I supposed to get shorter bolts and use lock washers?