Nice pic Bob.
Appreciate you putting it up.

There would be some advantages to having an X bar as shown other than to help in the body flex dept.

I would guess that you'd want to have a stiff frame.
If the frame is flexy and the body stiff I can see some damage happening in the body mount areas.

Sometimes we get locked into doing things a certain way.
The cowl hoop I planned to put into the 31 was going to be round tubing.
(Not to mention finding a guy with a tube bender in this small town.)
Sure looks easier to make it from 1" x 2" x .090 wall rectangular tubing.
Not to mention tying it down wouldn't require overly fancy tabs.
And tying the steering cross-bar to it would be easy.

Since the fuel tanks on my 31 on 32 rails roadster project are going in the frame under the body I have room for a spare tire.
The X bar would make life easy there.
As well as make it easy to put a piece of plywood in that separates trunk from cockpit.

Good stuff....