Razor + two chemical Cocktail - it worked!
Success - I experimented a lot and fortunately the result was another "mechanics.SE save".
You're about to take a razor blade to a car, have a large glass of strong whisky first to rock-steady your nerves. I recommend Heaven Hill
(if you can't get that, Macallan 18 yr old will do)
2. Flat, straight, naked, square razor blade
Experimentation suggests this sort of thing will NOT work:
Take off and dispose of the safety device
3. Drown it in the magic cocktail of GoofOff and WD40
I tried a number of products on different edges. For me, drowning it in BOTH GoofOff and WD does it.
I simply poured a huge amount of Goofoff on to the surface / some shop towel (WATCH FOR DRIPS) and basically held it there awhile.
(As always with Goofoff, in fact it seems you really do NOT need "a long time", it seems to either work or not; the instructions suggest the same.)
So get the Goofoff in there, and then spray the hell out of it with WD.
Some internet tips suggest putting the chemicals "on the edges". I found that was basically impossible. Just drown it (including the edges). Indeed Goofoff generally softened the damned stickers, rubbed off the pathetic top plastic layers anyway, so it's all good.
Adopt "AS MUCH AS POSSIBLE" approach to the chemicals. Perhaps have a friend continuously spray the WD as you work, even.
Of course take care / test, but I had NO - ZERO damage to the paint from the Goofoff.
4. WATCH FOR DRIPS down on to, say, plastic light covers
I'm pretty sure one or both of the chemicals will streak light covers - beware
So it worked for me, I just razored a few pieces, then soaked again, razored, soaked.
• It seems you have to hold it so that the tiny edge of the blade is basically perfectly flat to the paint surface
• Just do tiny pieces at a time (see below). Forget the idea of doing a big chunk. I did ~70 pieces
• Incredibly you CAN get it literally "in between" your car and the sticker. It works. The feeling is amazing once you are in there
• One mistake and you're screwed. It seems to be something where the outcome is either perfection or total disaster :/
• Forget gloves. If you're sensitive to goof-off, no go. Unless you're like a brain surgeon used to working in surgical gloves, this is going to be an unprotected procedure
• You'll need small fingers since the back of the razor, will only be raised a matter of millimeters above the paint to achieve the angle mentioned
• FORGET the idea that "after getting a start, it will peel off in one big piece". Nonsense! (If it was that easy a sticker, you wouldn't need all this, you'd just get under it with a fingernail then pull.) My one came off in ~70 pieces, I counted.
• It really does NOT work w/ just WD. And it really does NOT work w/ just Goofoff. In my experience. For me and the "EZRideMotors" sticker of death - the combo worked.
5. Another mechanics.SE save
As Jeremy Clarkson says, know you got soul. Thank goodness for this web site.
Tip - I wish I'd thrown a piece of paper on the concrete where the 70 hideous, surely toxic, pieces of metallic horrible sticker stuff polluted my driveway, it took ages to clean up.
And to repeat I guess one has to be super-careful with drips on to taillights.