I was asked to make a version of BeamStop main beam controller that could also manage sidelights and toggle between side and main with a single button (like a Caterham).
I've done this, so I made a few in case anyone else is interested. They cost £85 plus postage (or I can bring to Stoneleigh):
The unit is connected to 12V permanent (so sidelights can work with ignition off). It only draws 5.5mA so should not be a significant problem with battery drain.
There are 3 relays (not included) – sidelight, headlight power and dip/main.
With ignition off, the headlight button will toggle sidelights.
With ignition on, the headlight button will toggle sidelights/side+headlights/off [repeat]
With ignition on and headlights off, the main beam switch will turn on the main beam while the button is pushed (i.e. flash function)
With ignition on and headlights on, the main beam will toggle (latch) between dipped beam and main beam.