Making a new mantle

Here is the lovely cover Penny made for our holocaust survivor torah scroll (appliqué on blue velvet):

 Some detail of the appliqué:

It is constructed as two panels of the same size, with side seams and slits, lined with white:

The approximate dimensions of the panels (finished size) are 17-1/2" wide x 28-1/2" high.  In some places the appliqué is becoming frayed, and there is wear at stress points at the side seam opening.

The platform

The panels are attached to a fabric-covered rigid (wood?) platform 13-1/4" across, with cut out circles (2-1/2'' diameter), centers approx 4" from narrower ends:

The platform is covered both sides in the blue velvet.  I'm not sure exactly how it's connected around the openings, at least partly hand-stitched? Nor can I see any side seams, as the side panels and lining cover the sides of the oblong.  (Was the oblong sewn along the outer edges, leaving a gap for turning right side out, then had the rigid material inserted next, and finally the circular openings finished by hand?)

It looks as though the velvet cover and lining were attached together and THEN hand stitched to the covered platform.  Here's the inside view:

outer cover machine sewn to lining, then attached to inside top

And here's the view from the outside:

I wonder if there's a way to insert the rigid material AFTER the decorative cover and lining are sewn (by machine) to the top piece.

Wrap-around?

I also wonder whether, instead of constructing the outer cover in two panels joined at the sides with slits (which is vulnerable to wear and tear at the slits), it would be more stable to have a single continuous outer cover, overlapping at the back.   That would give the necessary ease for slipping the cover on and off, but without pressure points at the sides.

With a 7" overlap, the outer cover would be approx 42" wide x 17" high (finished).