DaveW. Thanks for the quick reply. I was thinking of a timber just the width of the exposed cross member (red marked area) and not putting any pressure on the area where the rear valance goes under the back which has the 3 screws.

How far back behind edge of the valance does the cross member actually go?

Thanks again.

P.S. are you the author of the buying and maintaining modern Morgans? If so got it and excellent book.