3M and other companies make rubber eraser wheels that go in a drill and will take off pinstripes, decals, and other types of stickers fairly easily and won't damage the paint underneath.
I've used them before plenty of times and they are worth every penny - and they don't cost a lot of pennies, either.
Something like this, for example: https://www.amazon.com/Whizzy-Wheel-Sticker-Remover-Adapter/dp/B00FJF0O2K/ref=sr\_1\_6?crid=3SBRE2129V2Q6&dchild=1&keywords=rubber+eraser+wheel&qid=1622762616&sprefix=rubber+eraser%2Caps%2C197&sr=8-6
I have heard a rubber wheel like these works well.
Rubber wheel Whizzy Wheel Car Decal and Sticker Remover with Drill Adapter Kit https://www.amazon.com/dp/B00FJF0O2K/ref=cm_sw_r_cp_api_glt_fabc_1S4APY16TQDBS6YEWA12?_encoding=UTF8&psc=1 Used it in my Yamaha to remove decking. Acetone can also be used and bar keepers friend is also a great cleaner on fiberglass
One of these will save you hours. Used one on my truck and it did wonders.
Whizzy Wheel Car Decal and Sticker Remover with Drill Adapter Kit https://www.amazon.com/dp/B00FJF0O2K/ref=cm_sw_r_cp_api_glt_fabc_PF1CBCQ72HXD2VEWNH68?_encoding=UTF8&psc=1
Do not let the sticker or surrounding area get too hot as it can damage your paint. Once removed any small residual goo may require goo gone, wd40, or a clay bar to remove. Finish it up with a bit of polish and then wax and it will be like it never happened.
I've debadged countless vehicles with this method and if you go slow and are careful it works.
Just finished removing a gloss black wrap from my roof with similar deterioration. Typically happens from the sun and exposure to elements over time. Tried all the traditional routes of heat, plastic scrapers, etc. Only thing that worked was a power drill and an eraser wheel.
Something like this: https://smile.amazon.com/dp/B00FJF0O2K/ref=cm_sw_r_apan_i_HTYVT463NQE4B3AH9S3R
I've seen other people use a steamer as well. If you have access to that, its likely a bit easier.
A mix of solvents (brake cleaner, acetone. Stuff like that but the stronger the eaiser itll be), heat gun, plastic scraper (or maybe this thing, not sure how well it works but its supposedly works great), and a lot of elbow grease.
Use one of these all the time to remove adhesive on vehicles
Whizzy Wheel Car Decal and Sticker Remover Tool with Drill Adapter Kit, Rapid Decal Eraser Wheel, Pinstripe, Adhesive & Vinyl Decal Remover https://www.amazon.com/dp/B00FJF0O2K/ref=cm_sw_r_cp_api_glt_fabc_NZ9QKYK87HDJPZ62M0GD?_encoding=UTF8&psc=1
Check your local auto shops for a tool called whizzy wheel / pin stripe removal. You put it in a drill and it'll remove stickers quick and easy without damaging paint.
Use fishing line as op says below, then get a whizzy wheel
Whizzy Wheel would really help here.
https://www.amazon.com/Whizzy-Wheel-Sticker-Remover-Adapter/dp/B00FJF0O2K
​
I haven't tried the generic ones though.
I like using a eraser wheel. Very easy to use with a power drill
Is this a good one? https://www.amazon.com/Whizzy-Wheel-Sticker-Remover-Adapter/dp/B00FJF0O2K
Also consider an eraser wheel.
If you leave it on for a couple years they can get REALLY hard to remove, though. You have to use one of these on a power drill to remove it. On a $80k Caddy? No thanks.
https://www.amazon.com/Whizzy-Wheel-Sticker-Remover-Adapter/dp/B00FJF0O2K
These work like a charm.
Do it right, peel it off and reapply. Use this wheel for the residue.
Is this what you're talking about?
https://www.amazon.com/dp/B00FJF0O2K/ref=cm_sw_r_cp_apa_i_GNdJFbDHM3W9V
Whizzy Wheel Car Decal and Sticker Remover with Drill Adapter Kit https://www.amazon.com/dp/B00FJF0O2K/ref=cm_sw_r_cp_apa_i_9JqmDbXMBJMVK
I've had really good luck with these. You can get much more aggressive without damaging the finish.
If its truly heinous, you might have some luck with something like this:
https://www.amazon.com/dp/B00FJF0O2K/
There are no doubt several YouTube videos on these rubber wheel decal removers.
Something like this: Eraser Wheel