What I was referring to with the fuel not only applies to swiveling the wing in a flat plane, but in some cases wings are rotated 90 degrees downward before folding them back toward the tail of the airplane. If the fuel resides in the front part of the wing (which is now pointing downward), it may be difficult to overcome the weight and rotate the wing back up to a level position for attachment to the fuselage. This would apply no matter where the tank is located in the wing, although as you mentioned.....its usually inboard near the fuselage. A lot would depend upon the placement of the swiveling point. It could be a non-factor or an important consideration depending on both tank size and pilot strength.