Many of those adult players dream of having their own court. But we are still building a lot of courts. The typical tennis court does take up quite a slice of the backyard. Depending on your needs, the court can be made somewhat smaller. It could be anywhere from 100 to 120 by 55 for example.
Half courts are another possibility.
You can use it with anything but golf balls. They come back at you a bit fast. Once you decide on the size of the court, you need to choose a surface. For practical reasons, grass and clay are rarely used in Wisconsin. It has to be groomed and raked daily.