I first saw this in Calclimber's van, and the location is a copy of his install. There is more
http://www.sportsmobileforum.com/viewtopic.php?t=374
Here's my install:
I had trouble getting the holes straight so I wound up using a few small drill screws on a 12" 1/4 ratchet extension, as I could extend a phillips bit doing this. Great plan until the second hole and the cheapo drill screw broke off.
The aluminum is pretty easy to work with but you have to be careful not to wallow things out. Here is the monitor strapped in. I added a velcro strap under the bracket as this allows insurance against bouncing out. I also decided to use the bracket and velcro so I can easily remove the sensor and use it anywhere.
My worst fear was poking through the front of the plate. As you can see the install is invisible as I managed to use short enough screws. I haven't put the monitor up yet as I need some velcro from Lowe's.
The bracket was actually very strong and I considered just letting it ride, but visions of my sensor bumping down the road at 75 or falling out on some dirt road led me to add the velcro. Of course it's all supported by two small screws in aluminum, so we'll have to see how those hold up.