Well... I finally made it out to both of our local `big box' `Home Centres' and, unfortunately, wasn't able to find the exact box you used. But, I was able to find something similar that might work.
The ones I found have straight sides with the wiring openings more vertically oriented which makes for less intrusion into the inside. They also seem to actually be a tad bit thinner, width-wise, even though they claim to still be `single' boxes. Plus there are less `extra' protrusions into the inside which, hopefully, will make both the `trimming' and `padding' a lot easier.
Now that I finally have something to `play' with the next step is going to find just what adhesive / glue / whatever is going to provide the best `hold' / `grip' with the plastic these are made of. I am hoping to be able to add on a `tongue' that will raise the `attachment point' higher up along the back of the installed scanner so that I can use one of those GARMIN `buttons' to mount it onto one of those `slip-in' type mounts and allow it to be able to swivel whenever needed whether it is hanging off the dash or maybe even a belt.
Unfortunately, it is now High School graduation time and we have a graduate, with all that brings, to deal with. {WAN GRIN!} On top of that our other child is transitioning from Middle School to High School and our school system likes to make a big deal about that, too. And, of course, the 2 `hoo haas' overlap and expect parents to attend *both* `ceremonies'! (And they are being held in 2 different towns that are 15 miles apart. [That is one of the `prices' one `pays' when one lives out in the country and has to deal with a rural school district.]) {GRIMACE!}
I'll try and get some pictures of the work and the finished product that I can get posted after all the `shooting and shouting' is done. {VB GRIN!} Thanks for the inspiration!