YOU SAID:
Don't let him stop and unpack his trunk!
INTO JAPANESE
彼が立ち止まってトランクの荷を降ろさないようにしてください。
BACK INTO ENGLISH
Don't let him stop and unload the trunk.
INTO JAPANESE
彼を止めてトランクを降ろさせないでください。
BACK INTO ENGLISH
Don't stop him and make him take down the trunk.
INTO JAPANESE
彼を止めてトランクを降ろさせないでください。
BACK INTO ENGLISH
Don't stop him and make him take down the trunk.
That didn't even make that much sense in English.