I know when I was building my bike.....I planned on making it legal in "all" states - as I never know for sure what states I will end up riding in.  I didn't want a plate stuck up under the rear fender and hidden by the tire like the sportbike guys do...and I didn't want a vertical plate bent around a frame on the axle like the bobber/custom folks do, and I wanted lights that were bright and visible in direct sunlight.  I didn't want to give anyone a reason to pull me over for an equipment violation.

In most states the brake/tail light needs to be visible from behind....and having it located low down on one side of the bike may not satisfy a cranky officer.   (However.....I sure see a lot of bikes done that way and they don't appear to have problems.)    


http://massmotorcycle.org/content.aspx?page_id=5&club_id=769540&item_id=9361

The words street legal and bobber should never be used in the same sentence.
For the most part patrol car cops unless they ride generally do not know all the technicalities of motorcycle laws. It's the motorbike cops who will get you. For me I chose the vertical tag mount (not legal) but for safety reasons I opted away from the tiny, barely visible tail lights that normally sit atop these mounts. I went with a 4" LED trailer light from PepBoys for $35. And though it's not asthetically pleasing even if the sun is hitting the driver behind me directly in the face he can still see my brake light engaged. I don't however have turn signals that work. I have "dummy" signals mounted but they are not within the 9" seperation in the rear required by California law.
The only thing I've had an issue with it my yellow headlight which is actually legal in California.

After some digging I found this

http://suzukisavage.com/cgi-bin/YaBB.pl?num=1429671766/0#0