Bear in mind, however, that at least for official arduinos the "Vin" port is actually going first through a diode. So it's Vin minus 0.7v. Also, the diode can't sustain more than 1amp, which is plenty for those two fans at 11.3V, but you wouldn't want to go too crazy.

Your photos only appear as thumbnails for me, so I can't quite tell what you're powering from (the 12v input, or the "12v output." The latter being the only one that goes through a diode.)

First I identified where I could get 12v off the board.

Next I removed the 4 socket head cap screws and the plastic standoffs because I needed access to the back of the board.

Then I took a tiny drill .040" and drilled the solder out of the holes.  I used a couple of pins I had salvaged from an old circuit and soldered them in place.

Next I taped the wires for my fan to the end of a steel rod and used it to pull my wires.  I stopped at the back of the case with my black wire and ran that back to the front following the same line as the wires for the lights.  I ran a second black wire from the front along the same line and out the back of the case following the red wire the rest of the way down.  Now I had my switch leg ready for a switch.

I attached a fan for the electronics and soldered both sets of wires to a fan connector.  I finished it off with some electrical tape and covered it with the white heat shrink.