Nahhh, you're not in over your head.
Your car sounds a lot like mine. I had to replace the floors and rockers. Then, when I stripped it for painting, I found that almost every panel had been dented at some point. A few of the dents were competently repaired, but most had thick layers of bondo, sometimes applied over untreated rust!
Anyway, I sanded it all off, hammered the dents out better, reapplied the body filler, and painted it. One panel at a time. At the outset, I had virtually zero experience at this, but it all seemed pretty logical and I more or less figured it out. I'm a lot better at it now than I was at the start--and that's the idea, right? Same thing will happen to you. When you're finished, it won't be perfect, but you'll be intensely proud of it.