I also have an OBS (96) F250 with the alcoa rims. They certainly have a few issues as you guys describe from clear coat damage, and I've seen what you described on many aluminum rims over the years, so i completely understand what ya'll are saying.
If you start googling the issue I'm experiencing, it quickly becomes obvious that this is a known issue. There's plenty of discussion on it (no i didn't realize it prior to starting this post), and to cut to the chase, I'll tell you what i understand the best course of action is going to be.
I'm literally at the dealership as i write this, I of course discussed the issue with them and (I'm here because they orderd new back outer rims again for my truck)... I told them the consensus I got from research was to use rubber valve stems with the TPMS, versus the stainless steel bolted in style. This needs to be done from the start on brand new rims before any corrosion has started. There is quite a history of air leaks from the corrosion (on the inside of the rim at the valve stem sealing area) and the discussion is all about galvanic corrosion (or bimetalic corrosion due to the metal valve stems).
The service manager checked with the techs and they have the rubber ones, so that's what's going on my new rims. They said as long as i was good with it, they were good with it.
So... we'll see as time goes on if this was a wise decision. I'm really hoping so, i don't want to be back here a 3rd time for the same issue. If we don't try something different, it's just going to happen again.