With your mod folder enabled, can you load into the game without RPH? If so try launching RPH after loading into single player, this helped me as my game for some reason always crashes when launching directly through RPH at the R* screen and I couldn't fix that no matter what I tried. As far as I recall I used to get something like DirectX or Direct3D watchguard ended as the last thing in RPH log, but I would need to double check.