Mods are indeed allowed on Red County Roleplay, TXD mods such as skins and vehicle mods. Any mod considered a hack or a cheat, usually a CLEO, that gives an advantage is not allowed, and will result in a ban.
Although, First Person is allowed, and so is ELM. But, those aren't gaining any advantages against other players.
I hope this cleared your vision up, just post again if you have anymore questions.