Blender review
Before moving a light stand across a small room, I’d make a quick version of the setup in Blender. A wall, a stand-in and a camera are enough to see whether there’s room for the frame I want. Blender is free, and the same scene can hold both camera angles if I’m deciding between a wide shot and a close-up.
Rough out the camera angle
I’d set the camera to perspective and enter a focal length close to the lens I plan to use. A longer focal length narrows the view. If I’m trying to match a physical setup, I’d also enter the sensor size. That makes the frame a better guide to where I might put the camera. Krita™ is a quicker place to sketch a few compositions when all I need is a flat storyboard.
Move one light at a time
A rectangular Area light gives me separate width and height controls, so I could start with a shape close to the softbox I have. I’d change its position, check the shadow direction from the camera, then try a different size. I’d leave textures and decoration until I know the setup can fit.
Anabel’s take
I’d use Blender when the camera has to fit between a wall and a stand or when I want to compare two angles before setup. For a single straightforward frame, a sketch is enough. Once I’ve chosen an angle, I’d take a reference frame to the set and judge the actual light there.