The Proper Way to Use GTA Mods is Just Like This
Youtuber BlackSmoke Billy is definitely one of the better modders when it comes to GTA. Most people mess around and cheat with the game for purely evil reasons (cheating or griefing in multiplayer) but not good old Billy. He's rather mess with as little as possible just to hopefully pull off some sweet tricks in the game's massive sandbox.
With just the use of a speed mod to make this truck simply go faster (about as faster as it might travel if going down a steep hill) he's able to jump the semi, detach the trailer in mid air, and then catch it again back on the ground.