For anyone that comes here looking for answers, we have a custom built smoke generator. it’s simple but effective. I was a little worried about the pressure but a quick Google search confirmed that the LP gas regulator would limit pressure to 11 in H2O. Perfect for the operating pressure of the EVAP system. With the vehicle off the canister vent valve will usually be open and the purge valve closed. I used this configuration to introduce smoke in through the vent valve to an otherwise closed system. Sadly the smoke escaped above the fuel tank so I’ll need to drop the tank or pay Ford to do it for me.
Thanks @Nick for encouragement to just smoke it and @pschaider for telling me about the smoke generator.