It's not necessary to remove the door to access the fender, in fact, it's usually the other way around as long as you remove the inner fender splash shields. But that'll make it easier to paint that A pillar anyway.
Haha, when your bolts come off... Splash guard lower bolt wouldn’t budge and the fender nut by the door was caked in crud and wouldn’t budge either even after soaking it a day before with PB Blaster. I had to remove the door to use my torch to heat and a good 1/2” wrench to carefully remove the nut without breaking the bolt stem.
I had one inner fender nut pop out, but I did get the bolt out without damaging it. It’s fun taking apart bolts that haven’t been touched in 30, 40, 50+ years.
I’m going to have apart and back together about 3 or 4 more times, painting it in sections. I will say it is way easier to assemble the Barracuda parts than my Firebird.