Spare capacity in transport bays?

[Weirdo]

(Tech Manual, page 239)

If a transport bay is carrying a unit but that unit does not completely fill the bay, can the remaining space be used for general cargo?

For example, a BattleMech bay can hold a mech weighing up to 100 tons. If the bay is being used to carry a 55-ton Griffin, can the remaining 45 tons of capacity be used to carry regular bulk cargo?

Thanks!