When my kids were small, the ladder got used more than the steps. They'd jump in off the diving board and go 10 ft to the ladder because it was there. They also realized quickly that in a 20 ft wide pool, they were never further than 10ft from the side, and would just go to the nearest side if the ladder wasnt closer. Then they'd 'walk' themselves down the side to either the ladder or the shallow end. This was only after they had been swimming for a while and had tired some but still wanted to keep swimming. In about a year for the bigger kid, and 2 years for the little one, it no longer mattered. A combination of being older/stronger and better swimming ability, and they could just swim corner to corner all day. The ladder made it easier for them at times but it wasnt particularly needed. Think about it, you'll have the ladder on one side. Half the time in the deep middle, the other side will be closer. They will go for that side and pull themselves back to the shallow end. By 6 years old they could climb out on their own at any side. They could climb out at the corners about 5 years old. Once in a while we have friends over with little kids (and with plenty of adults around) we just pull the kids out from the side if the ladder is too far away for them. Your kids will have pleny of supervision too, even if its just you and wont ever have to fend for themselves (alone) with the ladder. It definitely helps, but its not nearly as critical as you think.
My two cents would be to center the volleyball anchors and put the ladder right next to it on one side. Swimming 18 more inches wont ever matter. On the other side its18 inches closer
