this is the part that makes me wanna decide the own distance between the vehicle bone like you posted before.
Yep, you would set that with the values from the ini file.
Also i need to really have the prop invisible. I know that R* Editor have problems by showing or rendering things that are was set invisible.
You can't use R* Editor anyway, it won't record any part of the light that is being created. If you're bothered about a visible prop, use a golf ball with an Alpha level of 0. Using a prop makes this so much more simple, it inherits the movement of the vehicle, it translates that to the light, so everything works properly when the vehicle changes angle.
If you're bothered about the Editor, then you might as well not have any of the spotlight features at all, because none of them will appear in the editor.
I have to get back to adding some additional cameras to my replay system now but I think you should be able to get something working out of what's here.