Minok

Another ground option is to ground where other stuff is 'grounded'. IE the electronics behind the dash. The ground doesn't have to make its way all the way to the fuse panel, it just needs to get to the closest grounding point, which may be up in the roof or a-pillar or just behind the glove box.

Thanks for the insight into where the hot circuits are. I'm in a Targa 4, so using the unused PDK circuit is an easy solution.
So why not pull the fuse panel to insert your own hot wire at the backside (or wherever the PDK circuit wires attached there, if there are any, end up) ?