I don't know how many different trucks there are, but the huge lift truck looks wrong even on the A320. It's almost touching the nose. I would like to force it to something a little smaller.
It's not a matter of specifying the truck, it more an issue of *having* more truck models. We had more models in P3D but, we didn't want include outdated models that looked out of place in MSFS so, we'll add new models in the future, like a smaller truck with no towbar that can be used on small-mid size planes.
Once we'll have that, it would be best not to select them in the airplane configuration, because then you'll be stuck with them everywhere you go, when it's more realistic to have a variation of adequate models that all can be fitted to the airplane, and selected automatically at random.