I'd love to see more animated body parts of the sort you're looking for!
Crawling Claws/Hands (creature) by Zarathustra217 is very well done.
CEP has carts by Draygoth (at the top of the creature appearances) and CCP (appearances starting "Travel"). The latter have the older CCP horse models, though. The Draygoth models also work as "tails" for humanoid riders.
I made a
sleigh prototype to demonstrate how to make a moving cart, drawn by almost any creatures of your choice (as shown in the video link). Sadly, my modelling skills are no way good enough to make a plausible cart, but maybe someone here could oblige.
Carts (and other very long models) need careful handling in game. The default turning motion (pivoting on the z axis) looks most unnatural - scripted motion along a gently curved path of waypoints looks better. Also, NWN assumes that the space occupied by a creature is similar in all directions, so, however you set PERSPACE and CREPERSPACE in appearance.2da, either the front and back of the cart will clip walls and combatants, or the space beside the cart cannot be entered for no apparent reason. These issues are reduced if carts are only used in cutscenes or scripted activity, and never allowed to fight.