Nah, just put a couple of upholstery staples through the back piece there. They're too thin to interfere with the electronics, and it'll keep it flush for the foreseeable future.
Edit: I just looked up my purchase history. Out the factory, the N3DS XL comes with a 1750 mah battery. You can buy 2000mah batteries now (at least that’s what they advertise, no idea if it’s that much in practice).
why is there a german address on the back? I don't believe this was made in germany... Does nintendo just have their european offices there? Frankfurt isn't really the top location for that, I'd have expected some of the bigger cities there
Probably offices. The country makes sense since I'm in EU, but no clue about Frankfurt. I checked some of my other junk, and the Switch dock has the same address on it.