I use a pop-up toilet tent as an outside spray booth, others use pop-up fabric wardrobes (which are useful as they come with a hanging rail).

No other ventilation, but having as much volume as possible helps the overspray disperse mire before it settles.

But you’ll probably get orange peel regardless. The overspray tends to manifest itself as a dry surface powder. With a spray gun you can add retarder thinners to the paint, which lets the paint dry a bit slower and reduces the surface tension, allowing it to sit flatter on the surface.