I'm a bit wary about recommending this, but once you de-case a TV and realise how easy it is, there is no going back.
It is much easier to mount a screen securely (by the four corner mount points) than to try and make a TV fit in and wedge it tightly with wooden blocks. Your cab will be slimmer and look a lot better without all the extra stuff as well. As for mounting the chassis - you can screw that to the inside wall of your cabinet, or make a little shelf for it inside.
If going down the decasing path, you should do some research (ie google) on discharging the anode cap with a screwdriver. You may or may not want to try temporarily removing all or some of the connections with the chassis and control board as well, and reconnecting them once the tube is mounted from the four corner mounts (all TV tubes have these). This will make your life a bit easier and safer.
The second worst thing that could happen is that you do something dumb and damage the TV. If that happens, at least you know CRT TVs are so cheap these days that it hardly matters. We all know what the worst thing that can happen is, so be safe and smart not dumb and ....... At least there are two of you (so look out for each other and be safe - am I repeating myself?).