I started to discover in the other forums about e-levels that is possible to hack through GBA according to what I made my levels for myself to create levels from scratch using SMB3 workshop with SMB3 rom to figure out the vision of what my levels suppose to be when I set up 4-byte object (3-byte) and 5 byte-objects (4-byte). So, this video below shows you that I just finished the 1st custom e-level such as "Zevit Grotto" which is an underground level. https://youtu.be/f7MRw7Rx0wk
So, its basically easy to save levels ONLY with M3L file so that you can figure of your vision of your levels can turn out to be better even though you edit levels through SMB3 version in GBA. I might post pics soon, but what do you guys think?