As far as I know the main thing to watch out for is red lights, they can be to the rear of the car, but the further ya go forward the more you risk harassment from the local constabulary. Generally speaking for the streets flashing lights are a no no, although laws against them are pretty vague, they attract a lot more bad attention than good. Though there's a lot of available strobe lights, they are there to be used while parked. Another type to avoid is fog light types directionals, the general thought is that they can blind people so theres laws like height limitations for them. a few years back there were requirements for covers on lights mounted on jeep and truck roll bars, in some states but I think that's largely been relaxed.

I've seen some pretty extensive light jobs on the roads, so I think there's not too much said about LED light strings and so fourth. I guess if you stick to marker lights that are not red and don't flash the rest is all good. There's probably some illogical conclusion that could be reached but I think you'd really have to work it to pull that off. I might advise a separate switching system for the artful auxiliary lights just in case. The unexpected has been known to happen.

nothing blue at all in CA. Follow the rules for marker lights and you will be ok.

www.dmv.ca.gov/pubs/vctop...d12c2a6.htm

- Bart

Red can only be on the back
White can only be on the front
Yellow can be anywhere, as far as I know
No blue whatsoever
Not sure about green
Flashing is generally a bad idea as it would be confused with signals and emergency lights.