Traveller fleets of what ever system are the fleets from WWII. ...However, there is not a torpedo, so the carriers and fighters and Gazelle does not make sense. ...
If the Traveller fleets lack a "ship-killer" small-ship weapon, then perhaps they are not in fact "the fleets from WWII." Traveller fighters - and therefore carriers - are pretty pathetic compared to the performance of their WWII counterparts because the most powerful weapon for something that small can be stopped by a nuclear damper. So, perhaps the WW-II paradigm is not the best paradigm for the fleets of Traveller.
Tactical naval combat is ultimately about being more successful in applying destructive energy to a chosen target than that target is in applying such energy to you. WW-I made the battleship queen in that role - big gun, well-armored. WW-II made the airplane queen in that role - vulnerable but plentiful and hard to stop, and packing a deadly punch.
In the high-tech Traveller universe, NEITHER end of the spectrum is very effective: small craft can't carry enough punch and can't deliver without becoming impractically expensive, and the biggest ships pack good punch but can be taken out of the fight by a single hard hit from a spinal meson. Instead, the queen is the mid-size ship or craft: big enough to carry that big punch, small enough to be expendable. I'm not exactly a naval history expert, but I don't know of an historical paradigm that fits that model.
Without that piece, there is no reason for the close escort or for the destroyer. Hang some turrets on the supply ships and send a light cruiser along in case a commerce raider shows up at a fueling point, and be done with it. For policing, hang a PA turret on far trader and upgrade the MD to 4. Scouts are used for scouting.
I am presuming by your mention of light cruisers that you're dealing with High Guard, not Book-2. A light cruiser costs in the rough vicinity of 15-20,000 megacredits. A commerce-raiding High-Guard-design 1000 dT destroyer escort with a model-9 costs about a twentieth of that. While it is no match for the light cruiser, you can put twenty of the things in twenty different places while the light cruiser is defending one. Unless your supply ship likewise has a high-end computer - or is blessed with very good armor - it is not going to fare well by itself when the raiding DE shows up.
As for Book-2, well, there's no Book-2 "light cruiser" for comparison, but the same basic idea applies - cheaper means you can cover more area. Your best bet for the mission is the least expensive ship that can knock down the transport itself, since that allows you to cover more ground and obligates the enemy to likewise get a lot of lower-cost ships to defend the same ground. There are no Book-2 rules that I know of to cover a Gazelle's PA guns, but between its 5G drives and its Model-6 computer's ability to run a very good array of combat-related programs, and if those PAs behave anything remotely like the High Guard PAs, it'd have to be a pretty large and well-equipped freighter with a good computer of its own to have a chance against a Gazelle.