>3. Get strobes with faster durations, or wind those 1600s >back a stop
I was reading up on the Alien Bees, and the AB1600s t.1 at full power is 1/600, but gets longer as the power goes down. At 1/32, it drops to 1/300...worse for stop-action. It looks like AB800's are better suited to the task, given their full-power t.1 is 1/800.
In addition to the 1600's my boss lent me, I got 4 AB800s from a friend who doesn't need them for the weekend. I think I'm going to set up 3 of the AB800's and work those at full power, with the 11" reflectors. This may actually work.
I'd also planned to experiment during practice runs with my speedlights...one on the camera and one on the rail to my left, forward of me a bit. I can't get too close for fear of spooking the horse, but we'll see. Since I'm only taking one shot at a time, the batteries should last OK, but if I'm up to fast in shutter speed, I'll lose a lot of power, I think. We shall see.
Finally, a friend of mine (the one with teh AB800s) found the following write-up on PCB Einsteins when used with sports photography (a 2010 article). VERY informative, and what prompted me to look again at the Alien Bees' flash duration thing, and see if the smaller ones would be better. They just might be.