A typical dining room chair is like 18". My doctor told me to avoid sitting on the pot for more than about 3-minutes at a time, so that wouldn't be too much of a hassle and still have a conventional install. Unless you and other smaller people in your household really like it that low, it will make it tough on everyone else, and potentially a problem at resale time. The move is on to making them more chair height, not lower. Your house, you can do what you want, and a wall-hung, as said, is flexible up to the point where it would sit on the floor, but moving it later would be a major rebuild. An easily placed foot stool might be a solution that wouldn't impact every other user in the home or resale.