If you have a decent place to put an in-ground system it is recommended over any alternative including roof, wall and portable basketball goals. The price to performance ratio is much better for in-ground.
At minimum, 32” is required for one of our adjustable Ryval Hoops systems. This leaves room for the concrete pier and clearance for the adjustment mechanism. It's not uncommon to jackhammer a notch or hole in your driveway if necessary.