Good grief, skin exposure isn't going to kill you. Take a hard enough spill and not even heavy duck canvas will keep you from injury. If you ride correctly and lawfully, you will stay off the ground. If you want to get faster, then pedal harder and use gearing to your advantage. I ride with lycra shorts and a triathlon sleeveless shirt; I ride with traffic, 45mph limits on the main stretch, through downtown congestion, over gravel/hardpack trails, up and down hills, in the rain/snow/ice, and skin exposure just doesn't seem to matter at all. Besides, should you (hopefully not) go down, the first thing you'll do is throw out your hands. Long pants will not help your hands. Or you'll strike a hip. Long sleeves will not stop a hip fracture. Or you'll knock your noggin. Clothing has no bearing on helmet integrity.

Put on some shorts and ride, my friend. You might even get a tan.