I dunno, it seems like if you are skidding as a way to slow and stop, more effort is a good thing. Whenever I skid, I shift my weight forwards on the bike. The further out I put it, the less weight there is over the rear wheel. This makes it easier to hold the skid. If I wanted to stop I would put more weight over the rear wheel, forcing it to rub on the ground harder and slow the bike quicker. I run risers sometimes and don't have much trouble skidding but I don't hold them for 50 feet or anything. I've seen people with those MTB bar end extension things on their chopped down flat bars, maybe you should try that.