All I can think is if you play the variants with different textures completely with texture dumping on, and then put these in the custom textures folder, and then play MarioKart with the default version. When you want the alternative textures, enable texture modding for the game, and when you don't disable it. (I don't know exactly how to do this, but I know it can be done.)
OS: Windows 10 64 bit Professional
CPU: AMD Ryzen 5900X
RAM: 16GB
GPU: Radeon Vega 56
CPU: AMD Ryzen 5900X
RAM: 16GB
GPU: Radeon Vega 56
