So, let me be a real pain in the arse and suggest that if road rash is what worries you, use clippers to get the ground cover down to a level where it won't block irrigation or obscure pebbles, and if you don't have that much hair, leave it alone. Shaving increases the risk of wound infection by stripping the surrounding skin of its ability to keep bacterial growth in check and that's the source in the majority of infected wounds.