Re: 10" Splash
Experiment with it. Either with its own cymbal arm, and add on boom on a dog bone or stacker. Just move it around and try it. On one set I play, its mounted just above and to the side of the hats. On another set, it's mounted in front between two crashes.
Just try it and change it, then try it again. Maybe even think about how you use the splash. Do you find yourself hitting the splash more often right after you hit a crash cymbal or when you hit the hats while they're open? Put it close to whatever item you more commonly hit right before you hit the splash. The less and/or smaller movements you make, the better your control is while playing.