Which gas tank?

You have asked a very good question, 67Dart273, how is my tank venting? I have described the set up I have. I have driven it the past year without problems, the furthest I have gone was about 2 1/2 hours at about 70-75 mph over most of the trip.
For sure, I don't fill the tank until it is running out the filler pipe, but I've had no issues.
C