Sorry, I meant to say that you’d need use of the internet to install, but not afterwards unless you want patches. Yes, you could install from source. I don’t know why I didn’t think of that. Sysprep COULD do it, but that seems like a lot more work than just finding a way to temporarily access the internet with a machine, but everybody’s situation is different.
The problem with #2 is that from what I understood that is what the OP tried to do, and it wasn’t working.