[quote=@Invisible Man]
Yeah, I would like to think that the wall would be inside of the Arena. They would rent the place out for a bit, like once a month, and get the aspiring MIR newbies to just punch a random somewhere inside of the arena, or they just bring random chunks of concrete or rock along with them. The guards would allow them to do that, right? It might be a stretch, but I think it would be kind of funny that way. 
[/quote]

It would serve as a way to showcase new metas so I don't think the Center would have a problem with it. Just include the fact that the wall is in the Arena in your sheet. Other than that it looks good to go.