I can imagine that it would fit nicely inside mugen-sized cover, even against dual-cell battery (coil against the battery, rest in the empty place, at the end of device that is opposite to camera). The question is - can we extend the wires that are attaching cell to module, without affecting charging - in order to allow coil being little further away from module? I would think "yes", but...

Then, I would attach charging to +5V and ground testpads under battery, using flat cooper cables (so battery can still insert without problems). IT shouldn't be required per se, but one could attach hardware switch along the way, mounted inside cover, so it's accessible from outside.

As for your question - there are those decorative tapes that imitate carbon-fiber, that wanna-be motor-head attach to their cars, with the help of hair-dryer (glue of those tapes is softened by heat). I saw that some guys cut those tapes into phone/tablet shapes, and attach them to back cover. for sure - if correctly shaped - it would look more natural than regular tape.

/Estel