It's interesting to note that even the Military don't drop cargo through bomb bay doors these days - they roll it out the back of a Herky bird, Starlifter, Galaxy, Globemaster, or similar kind of aircraft.
You could translate that to Traveller easily enough, with the right design; a Fat Trader (Subsidised Merchant (Type R)) could drop grav-chute-fitted ISO cargo containers out the back on a low-altitude fly-by, for example. ALl that would be required is specially fitted 4-ton ISO containers with a self-powered Grav 'chute built-into it; yes, it would reduce the capacity for cargo within the container, but it would reduce the risk to military or co-opted (IMTU: Civil Transport Reserve Fleet subsidy program within the Domain of Deneb) ships performing the deliveries.
You could translate that to Traveller easily enough, with the right design; a Fat Trader (Subsidised Merchant (Type R)) could drop grav-chute-fitted ISO cargo containers out the back on a low-altitude fly-by, for example. ALl that would be required is specially fitted 4-ton ISO containers with a self-powered Grav 'chute built-into it; yes, it would reduce the capacity for cargo within the container, but it would reduce the risk to military or co-opted (IMTU: Civil Transport Reserve Fleet subsidy program within the Domain of Deneb) ships performing the deliveries.