In XenForo however, I have a lot of possible customizations, regarding some pre-made image and the possibility of adding a custom class for more personalization.
Is there any reason there isn't a simple upload button? If you need a simple image file you have in your computer, you are uploading it every time and adding a class for each one individually?
You may see this is a one-time task, and that you will not do it again. However in my forums we have some rankbars for "Teams" of some games we have, therefore we need to keep creating them.