I got the lapdock today. I looked up on youtube how to tear it down, and it turns out there's 4 screws on the back and 9 under the keyboard, which is a little tricky to pop out.

The Motorola Lapdock 100 is surprisingly small, but that's not really such a bad thing for a portable system. Inside there seems to be enough empty space for a RasPi A+ with the full sized HDMI port and USB port, or a RasPi 2B with the taller through-hole connectors removed, AND at least 2 USB drives for internal storage. All it looks like I'll have to do is dremel out some bits of plastic that are in the way, splice and solder a bunch of USB and HDMI, and maybe add a heat sink through the bottom of the case or put in a cooling fan. The cooling issue is a reason that the RasPi A+ may be better, even though it does not perform as well. However, the 2B doesn't generate much heat, so I'll try to make that work.

Additionally, there's a 10.8 V / 2200mAh / 23.76 Wh battery, which can be charged from a 19 V DC external supply and can be used to power the RasPi via USB. USB should be easy enough to splice 4 or 5 wires (usually isn't it just 2 signal wires and 2 power wires?... is #5 GND?), but HDMI (with 19 pins) will require continuity testing and pinout documentation to make it work, so maybe I'll look for a small adapter instead. The screen is very reflective which could be a problem for outdoor use; I may look for an anti-glare coating or film to apply to the screen. The HDMI should carry the sound to the lapdock from the RPi; if not, I'll wire audio output to speakers. I might add a stereo jack to allow the use of headphones.

priority to do list:

Remove plastic that's in the way with pliers and knife and/or dremel: done

1. Remove and re-wire RPi 2B through-hole connectors which are too tall. Two USB ports and the ethernet port will be moved to the large socket that originally held the usb/hdmi connector end, and then they'll be epoxied into place. One USB port will be used for an internal drive (although there's space for at least two), and the last one will be used to connect to the lapdock. This gives us ethernet and 4 external USB ports; one of the external ports can be used for wifi.
2. splice USB so the lapdock will power and detect the RPi properly: the connector is already the correct type (microUSB), so I just need to use 2 jumpers to wire the signal from one of the 3 USB ports over to the power USB port on the RPi, like this guy did: http://andreiprojects.blogspot.com/2012/06/raspberry-pi-modding-atrix-lapdock.html. I think that should work.
3. HDMI: this is going to be the hardest part. I either need to find an HDMI adapter that's small enough or do continuity testing to document 2x 19 pins / wires so I can splice it.

later:

1. wire GPIO so it can be accessed outside of the laptop on a breadboard (perhaps through the part that was supposed to hold the phone that went with the lapdock
2. add small heatsinks for CPU, RAM, & network chips, and/or add a small fan, perhaps add holes in the bottom of the case for air
3. add external laptop battery pack if the battery doesn't have enough power to last a solid 12 hrs.