That's a tough call, as Spike is already fairly humanoid. I'd say he might be a bit taller, and maybe wear a shirt and pants only because that's what would be socially acceptable to the ponies, but no shoes.
So, Gordon_4's signature was the first commission I ever did, and the first time I ever drew any of those characters except Rainbow Dash. When I look back on it now, I almost feel bad that I charged money for that quality of artwork. I feel I've come a long way and, well, I decided to redo it:
I will say this and this only, Justice...what is it except to be justified for a wronging? But is justice for this if it is also the same justice of what is morally right and wrong?