5200FC or 4200 would be a pain to use,,, unless there is an easy way to clamp the keel guard against the boat while the 5200 cures? (A light spritz of water will help the 5200 or 4200 cure.)
I'd use contact cement, tape off everything, apply contact cement where it needs to go with a chip brush, let it tack over, press KG in place, then either roll it with a laminate roller or hammer the entire area with a dead blow hammer.