Boat Lights Law

Where can I find information on trailer lighting laws (UK)?
The website of the Ministry of Transport resulted in nothing, and the site NTTA little. The trailer apparatus we have wheel arches protruding about 300 mm from the body of the trailer, and about 150 mm beyond the edge of the car is to be towed by. The width of the trailer (including the wheel arches) is about 1900 mm. We want light, using a trailer lighting board, but do not know if we need to put marker lights on the wheel arches (lamps complicate the electrical installation, as I have some advice to use). We have already placed large reflectors on the front and rear wheel arches. (Caravan chassis of the 60's, takes the boats, but not a typical Boat trailer)
VOSA are boys, so that there is contact information: http://www.direct.gov.uk/en/Dl1/Directories/UsefulContactsByCategory/MotoringContacts/DG_10012449 They want to tell you outright or tell you where to find what you need in the maze of government guff. Actually, it's in "The Road Vehicles Lighting Regulations 1989, as amended, "but VOSA will tell you the consequences.
www.DangerousTrailers.org Presents Stolen Boat Trailer.. Trailer Sway



