Sorry I took so long to get back. Here's what I got.
The front section of the tower is roughly 62" wide. The rear is 68" wide. That is a couple inches down from the curve at the top. Inside diameter, BTW. The distance between the front and back cross pieces is 7 3/4", and between the two connecting pieces (with the thumbscrews) is 21 1/2".
Hope this makes sense. Pics should show what I measured. Let me know of you wanted something more specific.