Please note how quickly these guys get dragged and how far they get dragged and their reaction to it. The japanese and their insane game shows and whatnot, but consider this contrasted with sliding along the same surface at 60 mph...
Kevlar is great, as is the stuff in all the new CE level 2 rated lined jeans, UHMWPE or Dyneema brand stuff. That stuff will be right up there with thick cowhide for protection.
Combine with some Forcefield Limb Tubes around the knees and some of the Forcefield shorts with armor on the hips and you should do pretty well if you come off the bike. As long as the pants stay on (wear strong suspenders and a belt to make sure they don't slide down and expose your ass... ideally they should attach to the bottom of the jacket with a zipper or something to avoid that.)