How to reduce the smell of fuel when transporting a 6hp 2-stroke?

I have a 5hp Tohatsu outboard (external fuel tank) that I use with an inflatable boat. I transpose the boat and motor in the back of an SUV with the seats down.

I have the motor stored tiller side down but there is still a smell of fuel in the car.

I know I probably can’t completely avoid the smell, but what can I do to reduce it? I was wondering if putting a ballon over the fuel connection could help?