I'd go for a the fused relay option - a much more safe and reliable solution in the long run.

On the XTZ you have several choices for getting a live feed, the most popular are by tapping into either the brown feed to the rear brake light switch, or the blue/red feed to the tail light; whichever is the easiest to get to. Those two are good options if you're mounting a relay under the seat. The other alternative is the spare connector under the dash, behind the panel below the clocks.

Be aware that the tail lamp option and the spare connector under the dash are both live when the key is in the 'P' position and removed.

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