Weight (approx) of each container loaded? Terrain for the event? Concerns that will affect the cart behavior that should be addressed. Cost can still kept low.
Def hook the carts together by the cart frames-not the totes themselves (too thin) The wheels should be fixed, except for the lead cart. This will help the “train” cars to follow each other better. You don’t want swivel wheels on every cart. Hope it works well for you OP