no, its not rich... its the idea that the exhaust comes out the back. You have a negative pressure with the rear stuff open pulling in fumes.
Two things to help, open your front windows or remove them whenever the back is open. The fumes will still come upward but will leave out the sides.
Secondly, if you open your vent for the cowl to bring fresh air in the dash, it helps a little bit.
Its just the nature of the beast, like running a pickup w/a topper and the hatch open for the tailgate. It will pull in the fumes... they do that from the negative air pressure. Your better off removing the doors but keeping the back shut. Or, opening all of it up at once.