Anybody use a charcoal canister on the fuel tank vent so fumes don't get into the car??

I'd like to use one on my Willys. I have a vent in the trunk but fumes still get in even though the tank vent is to the rear of the car.

I'm really after what car I should look at to get one for. These seem to be dealer items. I could go to the junk yard but there has to be an easier way.

thanks