Hey Leroy. It's been a while since I've hit the chemistry books too
I'm just basing this on a thread I read a while ago on paleoplanet. A gentleman on there who makes rawhide on a regular basis went into a good amount of detail on his process. You are right, baking soda is slightly caustic, but it's very close to neutral (with a pH of 8 ), and way less caustic than drain cleaner (lye is about as caustic as it gets, with a pH of 14). I guess the idea is to use the baking soda to bring the pH closer to 7 (neutral), and then a quick rinse in the weak vinegar solution to get it even closer to neutral. Why you can't just use a stronger vinegar solution is a mystery to me. All I know is this guy has a lot more experience than I do, so I'm just taking his word for it.
My thinking is a lot like yours - I'd like to stay away from chemicals as well. I think I'll try dry scraping next time.
Just a quick update - I started scraping the hide around 9:00 last night. My intention was to just go out and give it a stir, but I noticed that the hair was slipping so I went to work because I didn't know how long was too long to be in the lye solution. After about 90 minutes of scraping I was not even half done. I couldn't finish and had already dumped the lye mixture, so I just put some water in the garbage can and returned the unfinished hide. I'm hoping that the hide stays swollen until this evening when I can get back to finish the job. Since some guys just soak the hide in plain water until the hair slips, I'm assuming it will be ok. My understanding is the swelling of the hide won't go down until the pH gets back to neutral, so in theory, the hair should still slip just as well tonight. I'll let you guys know how that goes.