So i thought, why not make a sub-section in the trainers forum for steve skins to be submitted and applied to the steve trainer model in later updates? The mod won't be finished for quite some time, and between now and then there's going to be a fair few updates, so why not give people a place to submit skins.
There's a bunch of people who want to contribute to the mod but can't use modelling programs, can't script, and can't make music. This is something that a lot of people can do, and help with. You don't even need any special software to do it. All you need is ms paint and a reference skin, and you're set.
TLDR: Instead of individuals adding skins, why not make a section where people can submit them for later updates?