I've got a front brake on my fixie so my input is crap here. I did try to do a skid today at lunch in the parking garage on my way to my car. Don't think I got enough weight off the back as I couldn't skid the rear and the momentum of my pedals keeps trying to buck me off. Plus I was thinking of other things like my bottom bracket being stripped on the fixed cup side. But more on that later.

But to further ephemeralskin's point, I think skidding as you normally do and then shifting your weight back to the rear wheel would slow you down faster. But then having not skidded a bike since my earlier years on a coaster brake bike, my opinion is nul and void here.