Any way to make an Avatar from just clips?

Every animation asset that I've ever bought on the Asset Store includes a model with a Mecanim avatar. The clips are connected with the model which makes it possible to retarget the clips to another humanoid.

I just bought this asset and it turns out it's only clips. From what I understand this means it can't be retargeted unless the armature has the same hierarchy and bone names as specified in the clip. It's kind of useless to me this way so I'm trying to see if there's any way to accomplish Mecanim's humanoid retargeting with these.

Is there any way to create an avatar from one of these clips? Alternately, If I were to create or find an fbx with a compatible avatar, is there any way that I can use that to retarget the clips to a different model?