The rule of two doesn't have anything to do with the xmls, it's the pngs themselves =/
You need to resize yours to become that, the best way to do that and not cause any strange errors would be to extend them to the right and down so they becomes the right size.
16x16
32x32
64x64
128x128
256x256
512x512
1024x1024
Or 512x32 perhaps...
About all assets, there's no need to ship the level with all our assets if they are not changed, it will most likely cause issues, you extract them only to be able to see how they work and copy what we've done =)