If you want lounge privileges bad enough, why don't you just buy a day pass to the Admiral's Club? I think they're $50 - well worth avoiding the mess at the gate, especially during long layovers and irops. However, I'm not sure if buying a day pass at the DFW AC will permit you to use the SJU one, even if it is same day travel. Such is life when you don't have a lounge membership, though. Good luck and happy travels!