I do get where you are coming from with outlining all of the precautions you have taken, and I agree that the print is 99% likely to go just as fine as all your other ones, but there's no amount of planning or prepping you can do that will change the fact that putting a pile of flammable articles over a massive source of thermal energy is indeed a fire hazard.
This is coming from someone with a very not ideal setup that does not have great fire safety precautions. (It's inside a wooden hutch with a curtain draped over it for heat retention... 😬) I understand that my setup is dangerous, and I accept those risks. You aren't making yourself any safer in denying your own.
EVGA had PSUs that blew up. Samsung is still too afraid to put ultra fast charging in their phones because they were blowing up. AMD GPUs were starting fires like 10 years ago. Just because you bought nice parts, doesn't mean you aren't dumping a ton of power through very delicate and fragile components that at any second could decide to kill themselves and everyone around them.
Not trying to say you shouldn't do this because it's your setup and you know it better than people online, just that you should keep in consideration when making these decisions that none of the things you've explained will matter if a large capacitor goes pop, and if it's under a pile of sweaters you'll probably have a much bigger problem to deal with than you would have otherwise.