Howdy Mr, happy new year to BTW,
Mate, I did this for a living back in the early 90's, and I can honestly say that I am stumped.
The only answer
I have is to maybe select a finish that's not susceptible to scratching and use a brush strip.
I, like you, have Googled this exact same scenario, and like you, have drawn a blank.
Food for thought...
Cheers,
One Mad Man
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HSV, I've stopped trying to beat one (cause they've all been stolen)
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Current ride:
2007 TRD Aurion 3500s 128,000 Kays and climbing