Mods in MP
Before anyone freaks out, I'm not talking about mod menus
I'm a complete new comer to using mods in the game and for that matter, new to GTA 5 on PC (console since it came out). Are there mods that can be in the game but not used online? For instance, I've seen videos where people use their multiplayer character in Zombie mods and even have friends in with them.
Another example is changing or adding on different vehicles. I would love to do video of my multiplayer character in different great cars and bikes I can get from here and use in SP.
I'm just trying to avoid being banned from MP while at the same time being able to enjoy a lot of the car models I see here with my MP character.
I recommend using Director Mode (you can find a tutorial that I made for it, here) to play in Singleplayer with your GTA Online character. In that mode you can use trainers, car mods, etc. without any issues since you're still playing in Singleplayer, just with a different character.
Another way to play with a GTA Online character is by using a mod like Skin Control, or Emergency Uniforms Pack (I know that EUP is more of a LSPD:FR/police thing but it has a built-in character creator that let's you create a character) but both of these mods forces you into creating a new character instead of using your existing GTA Online one. However, you can save the character you made with both of those mods so you'll always have it.
As for the replaced/added vehicles, you can check AuthorSaulAlan's tutorial on how to replace vehicles here. And for the add-on vehicles, you can check out ReadMe's of the add-on vehicle for the install instructions