Three.js animation with Mixamo

My goal is to make a ROBLOX like customization system for my game, where a user can choose between hundreds of pieces of clothing and accessories for their avatar. Now, I would like to use Mixamo to animate my character, but Mixamo needs a fully boned rig to download the animations. Now that’s a problem: I need Blender to bone the rig, but each rig will be different since the user is creating his own character, and if I had all the rigs pre-made, there would be literally millions of combinations of characters!

The alternative, I’m thinking, is to use Tween.js, but that’s a really bad way since it’ll take a ton of work and time just to get a single animation, and it still won’t be as good as Mixamo.

At this point, I’m sure you have no idea what I’m talking about, so here’s an image to describe my issue:

Diagram

I hope the diagram made my problem more clear. Below I’ve listed some of the possibilities that could potentially solve this problem, but then again, not sure.

  • Maybe you can download an animation from Mixamo without a specified rig to it, so you can apply it to any character?
  • Maybe I just animate the base rig and then apply the textures for all the body parts (so instead of downloading all the rig possibilities, I just download all of the clothing textures)?

Any Ideas?

Thanks in advance!