Keep in mind that the top of that centering ring will be exposed to the ejection charge. You don't want pressure and black powder residue getting into your AV bay. You might consider a small plate that you can screw down over that hole to seal it up.I got the switch in and it works, but I had to cut a hole in the centering ring. The slot the wires need to run through to allow the altimeter mount end cap to pass through the tube is very narrow and shallow. I used 24 gauge silicon coated wires - they just barely fit in the slot. I would not use wires any thicker than that or you won't be able to get the end cap in the tube. I will leave the hole open until the build is complete to ensure things work before I plug it up. I may just cover it with aluminum tape for launches so I can get back in there if anything goes wrong.
The final product looks great! I really like the how the nose cone looks. Have a great flight!