That is a thought. In the location I am using in my ct it would entail a little more building as the right side wall for me would be the ct wall. A good consideration though. Either way if both the stationary wall and the sliding wall are frp on the inside and they are mounted over the shower pan area, there should be enough wall overlap with the trim that any water should end up in the pan. hmmm...
At it was, I was planning on using a full surround shower curtain. It is not on a track but has elastic through the top hem and just attaches to cup hooks.
It's what I use now without the walls.