Here in Virginia the State Inspection Station really watches when one adds lights to the rear of units. This is all with safety in mind I suppose where all lights have to be DOT approved and be integrated with the going into REVERSE MODE to keep the rear lights from coming on accidentally when traveling down the public roadways... Adding them to the sides of the unit up high doesn't seem to be a problem...
Anytime I have wanted to add something on the rear of my unit I always went to the local State Inspection Station and asked if it was all ok before dumping a bunch of money into it.
Not good when you go in for your yearly safety inspection and have to remove things before they will give you your safety sticker for the year...
Not finding the "DOT APPROVED" engraved into the lens on the rear lens gives them their first clue it seems...
Just saying from experience hehe...
Roy Ken