I use a ufo.....but...
You won't be running both lights on any twin-light shell with the oem lighting coil. The 'wire different' would have to be 'one or the other' thru a DPDT switch to run with the 45watt oem coil.
MAKE SURE that the 'red' (to the taillight/regulator) wire is always in the circuit. You cannot simply wire the oem headlight switch output to the center of a SPDT (or DPDT for that matter) with the two lights to the switched connectors. You end up with the regulator common to both lights. Call it a 'short' between the lights. They'll still both want to come on at the same time.
As said, you can wire a DPDT to do the job ( I have a simple diagram for that if you wish), or you can simply switch the RED and not the yellow. That leaves your VR (and taillight without some additional wiring) on all the time..............
Capiche?
BTW, the above is in regard to an 'H' model. Some others have the same wiring colors and setup, but not all.