Van's for its own reasons is refusing to give its customers any information on the electrical system, we have ask individually and as groups and they are not going to provided it at this point, so there is no safe way to make changes to the electrical system.
The second landing light would still be a high draw unit (compared to the other electronic items installed) and we do not know the capacity of or the load on the current landing light circuits in the switch and fuse box. With two landing lights drawing from one Sub D pin you may exceed its capacity. You may (as Van's will not supply data) also overload internal PC board wiring that was not planed for the greater electrical load.
Then there is the issue of the wiring in the left wing, the landing light requires two wires, one for constantly on and one for flashing on. As the wing to fuselage electrical connection device is only set up for four wires and three are already in use you would come up one connection point short. Yes this could be fixed but it will require an engineered solution.
This is just the tip of the iceberg, as time goes by and changes to the electrical system become required by regulation (new equipment required by FAA regulation such as ADS-B) or the need to replace failed equipment (like the Garmin 496 which should be out of production some time this year and will only be supported by the factory for a few years after that) with new production equipment that is cheaper to purchase than the cost to have the older unit repaired. With out the wiring information and limitations of the system provided by Van's we will have very few choices and the most likely will be to have to remove much of the current system and each of us at significant cost, will have re-engineered the electrical system so that we can be sure of what we have and its limitations.