Some calculations on the BalanceMod fighter counts:
A first level Light Carrier has 650kt * 40% = 260kt fighter bays, or nine bays. So it can carry 54 fighters minimum. If you take four engines per fighter (at 50 supplies each) times 54 fighters, that's 10,800 supplies per launch.
Since there is no room for that much supplies on board, the alternative is to add the required fighter bays, and leave them empty, or not use carrier hulls.