Window a/c security and insulation

[Ed.: I promise one day these projects will "all" be "done" and we'll get back to the stringed instruments.]

I've been meaning for a long time to do something about the window a/c in my office. Forget about physical security, I didn't even have the side panels attached. I would stick weatherstripping around the gaps and end up with a sticky mess every fall. This year it was time to do something better.

I found this Flickr set, which gave me the idea for how to fasten side panels to a vinyl window and to use PVC pipe to secure the upper sash. Another DIY enthusiast fabricated a piece to make the bottom area more secure, which I considered for a while, but in the end my particular unit and window to fit together  well enough.

Additional requirements included improved insulation and a cleaner look.

Step one for peace of mind was moving away from the back mud room roof area, which is just a short hop off the deck, to a side window that hangs off into the mulberry tree abyss. This corner is now accessible thanks to the replacement of the old bookcase with the new streamlined corner stack.

Then for some woodworking. I forgot to photograph the one piece that involves actual woodworking. Since I'm not taking it apart anytime soon, here's a drawing. This piece sits in the channels on either side of the window frame and snug down against the top of the a/c. It is quite stiff once slid into place. It's hidden from view by the new front panel.

Here are my plans I worked from:

All told it probably took about the same time to make as I've spent cumulatively scrubbing weatherstripping goo over the years, plus the whole thing is safer and quieter and I got to play with my Safe-t-planer.

Ok, it looks cleaner than the accordion panels and a 2x4, but I'm not claiming it's pretty! Should I paint it, countersink flat-head screws, or what?

Installation detail: