[EricH]

Ah, that makes more sense.

I'd definitely go over-bumper in that case. 10" ball, 15" to work with-3.25" for bumper width, so there's about an inch to play with on the far side of the ball. You could also leave a gap in the bumper to help center the ball going over. You'd have about 5" of gap available if you opted to use it, which could also make it possible for a full-height bumper to let the ball go under. (Haven't measured a ball to check.)

Decisions, decisions... seems like some prototyping might be in order.