The biggest downfall of this design is inaccessibility of the Lipo pack without taking the wing off. I thought I would fly the Pat a number of times before working on a solution, but decided to try it tonight. I took a 3s 2200 and set one end down in the fuse, just behind the #2 bulkhead (clear of the wing mounting bolt) and drew the outline of the pack end on the bottom of the top fuse deck, then cut it out. To clear the lipo's wires, I routed out foam and routed on down into the canopy foam so the pack's end "plugs" in. I then drew and cut out a lipo shaped hole through the wing at the appropriate location, making a fairly snug fit for the lipo.
Now I attached the wing and inserted the lipo through the wing hole and then "plugged" the lipo into the roof of the fuse. The pack's other end is now flush with the bottom of the wing after routing enough foam from the canopy bottom. I then attached a piece of glass tape on the pack to act like a "pull tab" so that it can be pulled out of the fuse/wing easily. Works like a charm and can't be seen unless the plane is upside down on your stand. Next, I will build a lipo to ESC extension so that the pack's power wires can be plugged in before the pack is inserted in the plane. Lastly, I probably will add glass tape over the opening just for more security, and replace the tape before every flight or design a permanent latching system to prevent the pack from falling out of the plane during violent maneuvers.
Hope all this makes sense.
Will post pics later.