I have the G 5 tower and it measures 18 3/4 x 20 1/8 x 8.
With the knobs approx 23 x 22 x 8 would work, plus padding Interior dimensions . It is really hard to find a case like that. I have built one out of wood with an open top and have used it also out of the 2nd door of the truck...I wrap the camera in a naugahyde wrap and it is easy to open the door and slide it out. So far the camera has been via truck, only in Arizona and Nevada.