Great thread! You do nice work. Thanks for sharing this and the details.
I pained my originally $50 82 Mustang last fall, after serious cowl plenum floor, and front body rust repair. Not much exterior rust at all. About $1900 including the gun and buffer.
I replaced the trunk, dutchman panel, etc, on the 66 Chevelle a couple years back.
Currently painting the new hood and fenders for my 66 Chevelle. The last guy did a really nice bondo, galvanzed tin and pop rivet repair in the 90s and a nice paint job. Its never been covered since I got it in 06, and its starting to bubble as you describe, as well as serious rust in the original hood, front fenders and doors. (Floors have had rust holes since I got it, now covered with X mat.)
Using all Dyna Coat from the local Carquest, and painting in the driveway. Currently trying to fix tiger stripes on the new hood. Never gonna be much of a body and paint guy.