As previously mentioned, the main point is that your mods can't give you any advantage over other players. Things such as handling and speed seems to be fairly easy to avoid, at least in my experiences. What is more difficult is the rate of bugs/opcodes, unwanted attributes like mods designed for single player and especially collision.
With collision, you may find yourself magically being unhittable behind your car or be undefeatable in shootouts because of your skin mod.
So main thing, test and test some more, if it isn't in compliance with Argonath rules, do not risk it and it is completely your own choice to install mods on your game and it is not an excuse that you didn't know if you get banned.