Anyone KNOW what the laws are, that is how much is allowed to overhang on the trailer and when you need lights or flags on the back on the kayaks?

Specifically in TN and Virginia. Headed to the Chesapeake and towing kayaks on my trailer. Just finished getting it ready, put a particularly long boat on there and got to thinking about this. Different states probably have different laws. Not sure what boats I am taking yet either.