I am not talking about an overweight situation. Max weight and max T/O weight is not necessaryly the same. Don't know what the case is in the XL.
Just because you are heavy when you start your mission doesn't mean you are going to be heavy when you encounter enemy fighters. Most times there are long transit times too and from the theater.

If you need to dogfight (Which by the way is highly unlikely in todays world.) you just drop your external loads.