1st Gen R53 Cooper S Trailer Light Connection

You need the converter so it doesn't draw from the electrical system.

You could try to wire it into the tail lights although I don't think the end result would be good. I'm curious to see what would happen u though

You also may want to consider different exhaust tips as the OEM configuration will render your trailer wiring uniform.
Meaning that the 5 or so wires will all become 1.

 

Maybe someone else can speak for the exact reason.

All I know is a tech at e trailer told me I would have issues without it and it is a necessity. These vehicles electrical systems aren't like the old mans buick and I didn't want to take any chances.

There's an OEM sticker on the windshield essentially saying that the electrical system is, let's say, "fragile"

 

The issue is load...or one of them...
The bcm is kinda like an amplifier..it converts electronic signals to higher levels to drive lightbulbs...the old ways was relays . Issue is if you splice in extra bulbs/grounds you change the impedance and load....and the bcm has partial failures...many folks that did the old "paperclip" upgrade to use the extra bulbs that were unused from rear fogs as extra brake lights learned this....
Other issues crop up....
But the typical fix with a modern system is to use the converter rather than to slice and dice or use an adapter harness. Yes...it is Initially more $$, but cheaper and more reliable given some time.

 

I think you'd be OK splicing in one LED, the current draw is small enough that I don't think it would affect the lights signal or BCN.

 

That's a wild looking mini. What aero kit is that?