Using an idea from dreNorteR i'm writing a program that will detect if you're running on an emulator with a V20 or actual hardware (at least, any emulator that isn't emulating the V20 microcode).
If I wanted to be evil I could submit it as a bug report
someone should make an interposer board that lets you stick a V20 and an 8088 in your PC and switch between them with a physical switch or something