Lightyear, I have a friend who owns a transmission shop and works on everything up to semis. When he moved into a new shop, he plumbed an air line all around the shop with about 3" (maybe 4") metal pipe. Same idea as your friend, except he wanted a huge air reserve at higher pressure. His compressor tank is taller than I am so it's not a small setup at all, but the reserve capacity of all that pipe is considerable.
IIRC, he said that when he first fired up the compressor it took nearly a full day for it to bring the entire system up to full pressure.
I like the PVC idea as long as the pressure is regulated well below the rated pressure as you indicate - much easier to work with. A broken pipe in a system like that won't just blow pieces around, it will also turn loose a considerable volume of air at pressure - not something to be close to.