Todd
To the best of my knowledge, you can disconnect the fuel pump without a problem. On older diesels, not getting fuels to the injectors would require you to bleed the injectors. The newer ones have protection for this. Thus, you could add a hidden weather resistant switch in the fuel pump electrical line. It will probably start and run for a short period of time, until the fuel in the line is consumed. You could also add a hidden switch in the transmission interlock switch line. But, depending how they hot wire to start the tractor, it could potentially still be started.
I'd need to see a wiring diagram of your 4-wheeler. What brand and model is it? I may be able to download a wiring diagram.
