Rockstar Provide Statement on Single Player Mods

After a media storm surrounding Take-Two's threatened legal action against GTA V modders, the company's parent have had a change of heart and reduced their stance a little. The company's FAQ now has a stance on single-player mods listed.

Question: Are PC Single-Player Mods Allowed?
Answer: Rockstar Games believes
in reasonable fan creativity, and, in particular, wants creators to showcase
their passion for our games. After discussions with Take-Two, Take-Two has
agreed that it generally will not take legal action against third-party projects
involving Rockstar’s PC games that are single-player, non-commercial, and
respect the intellectual property (IP) rights of third parties. This does not
apply to (i) multiplayer or online services; (ii) tools, files, libraries, or
functions that could be used to impact multiplayer or online services, or (iii)
use or importation of other IP (including other Rockstar IP) in the project.
This is not a license, and it does not constitute endorsement, approval, or
authorization of any third-party project. Take-Two reserves the right to object
to any third-party project, or to revise, revoke and/or withdraw this statement
at any time in their own discretion. This statement does not constitute a waiver
of any rights that Take-Two may have with respect to third-party projects.

Whilst this doesn't completely allow for uninhibited mods, it does clarify where the company stands. With the release of Red Dead Redemption 2 coming up, the company will likely be keen to avoid any more negative press.