Here is "Build 2" using the 5mm foamboard.
Hopefully it will take to the skies this weekend, weather permitting. I laminated the 5mm foam board with clear tape on both sides before airbrushing. The build used the first version of your plans, which called out for 3mm foam.
She is powered by a ELE C20 2900kv motor and a 3S1P 1200mah pack, both from TrueRC.com. For servos, I'm using a couple of 5gram units from Lazertoyz.com. A 4 channel Corona Rx with a Azzar antenna attached rounds it out.
I was going to go with a 5x5 APC prop, but didn't know that their props can only go on one way, so I used a GWS 5 x 4.3. Seems like it has plenty of power though!