How to bypass gazebo physics engine?

I'm working on an implementing a truck + trailer entity in gazebo. I have a state space model which I want to use to govern the physics of the truck + trailer entity by making a modelplugin . The state of this model contains position, velocity, etc. I don't want the gazebo physics engine to influence the behavior of my entity, in order to do so I use SetLinkWorldPose() to update the position (which I calculate using my model) of the entity every gazebo iteration i.e. teleporting the entity every iteration to a new position. The problem now is that I lose the velocity information of my entity when I observe it in Gazebo with some sensor, which makes sense because the velocity of the entity is zero in between iterations. But I don't want this. So my question is. How do I bypass the gazebo physics engine whiteout losing the velocity information of my model? Thank!