This isn't my area of expertise, but I'm pretty sure that golf ball speeds are so high that you wont get a small enough blur before you hit rolling shutter artifacts (skew). Stopping motion with flash is definitely the best way to go, because then the sensor readout speed (which is slower than 1/8000) wont matter. I think you do have to underexpose the background or choose a background that is small and close enough to light with flash. You might need four or more flashes to get enough power (since they have to be on their lowest setting to get the lowest decay time, which is the highest stopping power.) Hope that helps.