If you want to take fewer bombs that are allowed to be chosen in the hanger…. I dare say WISH GRANTED!!!! Select the size of the bombs you want, get on the runway, open bomb bay doors, and drop bombs until you have the desired number.
FWIW: there is certainly no shame in doing such things. While I don’t have his flight logs in front of me here at the office, I know of multiple missions my late grandfather flew with less than the max # of bombs or less than the max amount of weight allowed. I know of one mission in specific where his B24D took off with 6/250 lbs bombs, but the targets were Japanese supply ships.