Yes I believe your gonna find a problem above the tank. Like shown above there's lot's places for it to leak vapors. Pretty poor design if you ask me. Chevy tanks don't cor road like that because I work on them at work.

Our 05 durango had the entire tank replaced under a recall at 50K miles mainly because it would puke fuel all over the ground when it got full, no matter how slow you went with the fuel nozzle.

Then the new tank leaked and they had to put another tank in the truck the next day after we got it back.

Now 40K miles later I am getting the check engine light. I read the code about 5 times now and reset it. It's a small evap leak is what the code says. Takes about a week for the code to come back and I suspect a problem up at the top of the tank again. Our's sits outside so we don't smell it yet.