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cant tell if it will look totally naff
Up close in your hands, or using it across the whole of your house, it'll be awful.
For that short solid yellow line I drew, you'll only ever really see that first horizontal run and IMHO you will forget it's there by the end of the day. It's also accessible and low effort.
I'd ask in the diy thread about the box. My gut is that it's an old oem surface mounted box you could remove and replace with something slimmer. Although you might have to make a shallow hole in the wall for a back box. Even if you didn't have enough space you could have some sort of neat 5mm wooden Standoff that looks less like an engineer has installed it.
You could maybe even relocate a smaller one under the desk or inset somewhere else... It depends a bit how far from the wall the paneling is.
I was looking at this stuff but cant tell if it will look totally naff