Richard, did you read the OP's original information ?? You have such different elements and conditions, it ain't even funny. He has a single pole, 20' in the air with a double sided 8'x 8' cabinet.
You, practically have a building and I would consider that a single sided sign as to how those pylons are built. I personally have worked on several of those same signs. They are next to indestructible. You can amend it almost anyway ya want. The OP does not have those choices. Besides, you said .050 for him, but you used .080 for yours. Quite a difference, plus a weight factor.
So, again...... like I just said, what might work in one instance is not necessarily gonna work for another one, especially one with such different parameters. You are not comparing equally.