I got Kalani neutered when he was 4 months and he had just started lifting his leg to pee and still does. I live in an apt. also so use the pee pads. I make sure the pads are up against either the wall or side of the ex-pen and he will only lift his leg at those areas

 I thought about getting one of those little 'posts' but I know that my rascals would just play with it!