I think you're a bit too optimistic about what is possible with script mods. See some of the lighting work done by Mulledk19 on youtube to see what he has managed to do with indicator flashing, but he is perhaps one of the most knowledgable mod developers out there. Kit, who made the strobes mod, had tried to alternate sides but could never work out a way to do it.
It's definitely not a novel idea and is something that most people will think of when playing with lightsemissive objects (indicators, breaklights, headlights etc.) on modded cars. Currently though our problems are, as i said:
1 - If you were to assign different sets of lights to indicator_lf, indicator_rf, indicator_rr and indicator_lr, then you potentially have four different combinations of lights. However, currently there aren't any available scripts to control each of them separately.
2 - Using the indicators for your emergency lights obviously takes them away from being used as regular indicators. Really you could have your indicators serving both purposes but then you'd have your indicators doing funny things. Furthermore, whenever AI are driving the vehicle and indicate to turn they would activate part of their emergency lights, and I don't think this is just something that a script could easily disable.
3 - The orange glow around each dummy. This could be hidden or used effectively, but I don't think it could be removed altogether.
Really, the fact that there are four different sets of indicators means you could have a primary lightbar as functional as one you would have in ELS. Then you'd just need to add an environmental lighting effect as you see in els now. However, the mod support in terms of being able to control each of them separately is not available. As I mentioned, some headway has been made by mulledk19 but I'm not sure what the extent of his abilities are in that arena.