You're right, I think there's some confusion over what I'm asking. I should clarify:
Everything on my credit report is fantastic, with the exception of average age of accounts. I have a perfect payment history on all of my accounts, for as long as I've had them. I have an appropriate number of accounts, with credit limits well within the number described above. I know for a fact that I have plenty of available credit with Amex, whether I increase my credit line on my current card, or apply for a new one. These are not the issues I'm talking about here.
I'm asking simply about average age of accounts. And yes, I'm talking about opening new cards to counteract opening new cards. When two new cards have an age of one month, and two new cards show an age of 7 years, that comes out to an average age of roughly 3 1/2 years. Yes, the methodology is somewhat counterintuitive, but it if wasn't, I wouldn't have to ask.
Can someone familiar with American Express's policy regarding backdating the reported age of credit cards provide any kind of insight as to whether there's any reason this wouldn't work?