Not sure about a pass through version. Are you talking about vaping while charging an installed battery or using some sort of power supply or external battery to vape?
Couple comments on the design, I really really like it, feels good in the hand, even with that tank of a battery. I do strongly recommend targeting a cheaper battery with similar form factor, I was looking to see if the Floureon 1500mah's would fit (less than 1/3'd the cost), but was nervous they wouldn't.
Now, here's an opportunity: Those screw holes in the back cover can be eliminated for space for a different battery by using either a snap design or at least using a tab arrangement secured with some of those thread forming screws. You may even be able to reduce the height of the mod.
You guys that haven't built yet, my lesson was to be sure the + side of the output on the chip is soldered with the wire aimed downward. The proximity of the 510 to the chip makes turning the wire down and looping up a bit of a challenge, wire is big, and my higher strand silicon insulated wire wicked up some solder and became hardened.
Lastly some sort of holder for the screen would be uber cool . . . my fingers couldn't hardly maneuver it into place trying to hold the chip at the same time. I put a loose wad of electrical tape to keep it there, but getting it there took some time, kept moving it a sliver as I aligned the chip to its screw holes.
Great design, shortest one I have seen with a 2 or 3 day battery in it.