Mounting a bare 27" tube into a cabinet using plywood.

[Numbski]

So this is a bit of a cross-post from the Monitor/Video forum:

http://forum.arcadecontrols.com/index.php?topic=110236.0

In short, I think I need to do something along the lines of this:



To this:



In short, the monitor I have has never really behaved properly.  I have this RCA tube that I modified to work with a Wei-Ya chasis, and I can't find a frame for it.









Wondering if you had any suggestions or if there's a better way to do it?  Right now the suggestion I've been given is to trace the shape of the tube sans tabs onto a piece of plywood, cut that out giving me a rim or bezel to screw the tube to, then "somehow" mount that into the cabinet. 

Arcade Cabinet opening at it's narrowest points: 26.5x19.75
Tube at it's widest points (mounting tabs):  24.5x19.5

The direction I'm headed at the moment is this:

Basically, there's nothing across the top to support this.  Whatever I do, it will have to be along the sides.  I said above that I'll have about an inch between the mounting tabs and cabinet's side at it's narrowest point.  I also measured  the hole in the tabs to be 1/2 inch.  The "narrowest point" is a strip that appears to be stapled into place on the inside, presumably to hold the original plexi in place (which is long gone, I might add).  If I took a pry bar to that, it would buy me another 1/4 inch or so.  I could then measure off precisely where the plane is that I want the monitor to sit and perhaps glue+screw a 2x4 support on either side, then in turn mount my rim to that?  The bottom can be supported on the "shelf" that the current monitor frame sits on.  In fact, I could put a similar "stop strip" on the bottom that's comparably thin (would have to be about 1/8 inch) and that way this rim is supported on 3 sides.

Is there a better way to go about this?