Not being able to use svg images (because making a full moon and a well-detailed astronaut is very difficult), I opted for the Garigor Skin loading file in which there are bmp images.
I removed some folders and also some .ui, .lua and .css files that didn't concern loading but have other functions, (you should understand it when you open them) and it works well, even very fast.
For those who are unfamiliar with svg files, I think it's the best solution, for those who have an svg file, just replace the original one that is in the_skin_by_pongo.zip without having to create a new loading.zip file.