Reskinning Map Texures

Hello,

I'm looking to create some arty video of the skills in Cabal. To facilitate this, I need to create some space in the game with a consistent color background.

I'm not running a server, so ideally I'd like to modify some map textures in the client to be a pure color (black, green, blue for chroma). Where are these files located, and can they be modified to achieve this?

Beyond that, assuming I was running a server, would that open up any options? Like creating a new space with these parameters, rather than modifying existing spaces?

Thanks,
Terror