Yes of course, you can over load the BCM. If you want to go all out you could use the power that would normally go to the lights and put a relay in. If the lights youre currently using are the same watts and youre not adding any extra lights then you should be good to go.

Have you checked a common auto parts store for the bulb?

 

Now I understand the error signal. I am a retired EE. The HID bulbs have to be current controlled to survive. It seems rather simple to me that if indeed it measures a redundant "off" current for filament detection, and the unit has a current signal inside it, a resulting circuit can be added to eliminate the problem if indeed it checks this current sense during operation and not just when the key is turned on. So, does it continually check or only with the first instance with the key?? Jack