Tnt Minecart hitbox is too large

The hitbox of TNT minecarts is too large to stack them on a single rail, the hitbox of the rail is overshadowed by the Minecart hitbox, making single rail stacking difficult.

Replication:
1. Place rail down.
2. Place TNT minecart down on rail.
3. Attempt to place second TNT minecart on same rail.
4. Cannot reach rail hitbox without moving minecart.