Is it possible to have map textures on league of legends?

Yes it is. Map Skins League of Legends, search it up on Google, does it. Riot will probably never do it again. In the old days it was a lot easier to do something like this, but because of the current layout and art of Summoners Rift, they have to edit every bit of pixel to change the way the map looks. I don't know why they cannot do it if players that are not even working for Riot can.