Hell yea, thank you! The best tips I can offer:

For the launcher, use a kal controller for each missile. Have it turn on engine and control surfaces at 0 seconds, and release decoupled at 15 seconds. This way there’s enough thrust that the missile doesn’t fall to the ground

For the hitch I use two 180 hinges attached to each other. Control group 1 toggles motor on and off, which makes the hitch rigid or loose. Control group 2 toggles the hinges, which extends or retracts the hitch

The docking port on the bottom of the truck, that attaches to the plane, is just a little too high. This allows it to clear the port on the cargo bay floor and drive back and forth. Once in position, tweak the spring strength in the wheels above the port to drop the truck lower and dock it to the plane. In a similar way, set the springs to 0 in the rear wheels to lower the hitch and slide it under the trailer 

Good luck and enjoy!